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Dutch ground-to-air defences May 1940

Introduction

The Dutch Five Days' War is little known outside the Netherlands, but if two of its elements bear any significance beyond Dutch borders it are a) the massive airlandings around The Hague and Rotterdam and b) the (relatively) heavy German airplane losses.

The latter was partially due to a modest but effective AAA contribution. This essay intents to elaborate on the Dutch ground [surface] to air defences during the May War of 1940.

Prelude

When WWI started, the Dutch army had no ground to air defences whatsoever. The Dutch airforce had been founded just a year before when in July 1913 the first [leased] aircraft had found its home at Soesterberg AFB. Soon it was followed by three Farman planes. Although also some Nieuport's were procured, the Dutch airforce was a neglectable asset when war broke out. The events over Belgium and France soon proved that military airplanes would play an increasing part in modern warfare.

The military command realised that also ground-to-air weapons would be needed in order to provide the ground forces with the ability to fight enemy planes. Existing fortress and field guns were quickly modified to be suitable of targetting airborne objects. Also machinegun platoons were trained to target planes and balloons. A whole new ball-game!

In 1915 a Dutch artillery officer was instructed to organise the first AA unit of the Dutch army. He started off with designing a special tripod for the Schwarzlose heavy machineguns. In the meantime tests were developed with 5,7 cm, 7,5 cm, 10,5 cm and 12,5 cm guns for use against airborne targets. Positive results came from the 5,7 cm and 7,5 cm guns; the heavier guns did not meet the requirements for AA duty due to their slow operation.

In March 1917 the AAA became an official branch in the Dutch army. It was raised from the 2nd Regiment Fortress Artillery. It was initially equipped with heavy machineguns and the 6 tl and 7 tl AA guns, and later the [British originated] 8 tl. Also for a brief period German WWI guns of 4 cm were used [early twenties], but these were soon abolished.

Early AAA weapons

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6 cm AA gun

The Dutch lacked any sophisticated indigenous defence industry when WWI started. Regular mills and metal industries were able to produce existing weapons or produce shells and ammo, but the design of new weapons for heavy duty was a lacking skill. As such the first means of fighting airborne targets was found in modification of existing army guns. Many experiments were seen with almost all available artillery pieces. The only moderate successes were booked with 5,7 cm Krupp fortress gun and the 7,5 cm Krupp field gun.

Still during WWI the two aforementioned Krupp guns were modified by adapting them for vertical gun-action. The guns were installed on extended pivot-bases and equipped with large recoil brakes. The mountings were developed by the Dutch companies Werkspoor and Gusto [nowadays a well-known shipyard].The breech-blocks were modified and rudimentary instruments were installed. Both guns were initially used in fixed positions, later truck mounted.

  Gun 6 tl [57 mm] Gun 7 tl [75 mm]
Manufacturer: Krupp Krupp
Calibre: 57 mm 75 mm
Original duty: Casemate- and fortress gun Field gun
Material: Steel Nickel-steel
Gun weight [incl mounting]: 7,180 kg 7,980 kg
Elevation: 72° max. 75° max.
Fire rate: 3 rounds per minute 5 rounds per minute
Range: 3,000 metre [AA] 4,000 metre [AA]
Ammo: HE [3.2 kg] HE [6.0 kg]
V0: 450 m/sec 500 m/sec
Year of introduction: 1916 1916
Mounting: Pivot [fixed position 1916]
Pivot [Berna truck mounted 1922]
Pivot [fixed position 1916]
Pivot [trailer mounted 1923]
Number in service May 1940: 21 15


The guns were modified again during the interbellum. In the early twenties motorised AAA batteries [3 guns each] were organised. The guns were mounted on trucks or trailers and as such these units were very mobile. During the late twenties and early thirties very basic mechanical fire-controls were developed in order to be able to produce better and more effective battery fire. In practice [during the May War] these controls proved to fail for a number of reasons. Important reasons were that barrel-wear was not incorporated in the calculations and gun action was quite slow. The first element meant that reliable ranging was impossible, the second element caused guns to fire to soon or too late causing the projectiles to fall short or long.

Experiments with different calibre guns were undertaken too, even with heavy fortification guns, such as the 12-lang-staal gun, a classic first generation gun with dual loading. It soon became clear that these bulky and slowly operated devices were not suitable at all.

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7 cm AA gun

Due to the lack of sufficient numbers of modern AAA guns in May 1940, the old batteries were still in use with reserve-units during the May War. In the first hours of the war the fire-controls proved unreliable, and as such the gun crews were ordered to produce piece-fire. The crews soon got the hang of it and some units proved stunningly effective after a few hours of target-practise against the [seemingly] ever over-flying German transporters.

Another old battery that had been formed still during WWI was one equipped with British guns. It was a battery that had been procured of the British even during WWI. It had been involved in the air-defences of London that already in WWI was attacked by German bombers.

  Gun 8 tl [76 mm] Gun 10 tl [94 mm]
Manufacturer: Vickers Armstrong Krupp
Calibre: 76 mm 94 mm
Original duty: AA gun Navy Cruiser gun
Material: Steel Hard steel
Gun weight [incl mounting]: 3,800 kg unknown
Elevation: unknown 68° max.
Fire rate: unknown 15 rounds in 2 min.
Range: 4,500 metre [AA] 18,000 metre [surface]
8,000 metre effective [AA]
Ammo: HE [5.70 kg] HE [unknown weight] with timer-fuse
V0: 606 m/sec 900 m/sec
Year of introduction: 1917 1925
Mounting: Pivot [Thornycroft truck mounted] Pivot [trimmed]
Number in service May 1940: 3 [102 Battery AAA] 3 [101 Battery AAA]


The one 8 tl unit was still in service in May 1940, although the battery was not manned or used during the war. It had been assigned to a fixed position within the Fortress Den Helder [position Huisduinen], but as far as history files show it was not used here. The guns were totally worn-out due to intensive [British] use during WWI.

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10 tl heavy AA battery

During the interbellum yet another type of gun was introduced to the AAA. The fortress Den Helder defended the main Dutch navy base. This fortress was quite a strong base that comprised numerous fortresses and casemates. It had five dedicated AAA units. The 8.tl was already mentioned hereabove, and three modern 7,5 cm batteries were available too but in 1925 another battery was formed.

Three navy Krupp guns of 9,4 cm [10.tl] - previously intended to be used on board of a cruiser - had been modified for use against airborne targets. Although the battery was one of its kind it would proof effective and moreover the heaviest available battery of AAA available in May 1940. The three guns were constructed on a trimable pivot mounting, with their original armoured plating to protect the crew against enemy aircraft fire. The fire-controls were modified and adapted to AAA duty. The original navy gun-crew arrangement [of three constables and one commander] remained.

In total twelve 9,4 cm guns had come available to the SA defences, but since the wear of these guns seemed to be high, it was decided to form only one battery. These kind of decisions were the ones that stunned historians after the war. Apparently one bright mind had considered the duration of a Dutch-German war to be so extended that the battery would have its guns replaced three times, in stead of forming two batteries with one full spare for each of those.

New generation AAA

When the Dutch government finally started to realise that rearmament was an immanent matter to support the Dutch claimed neutrality the military was authorized to investigate rapid expansion of the AAA with modern equipment. In 1938 only six complete and working batteries of modern AAA [7.5 tl Vickers guns] were available, next to the aforementioned rather obsolete arsenal of older batteries. Some more Vickers guns were available but yet suitable fire-controls were omitted. It was not before the end of 1938 before new orders for modern equipment were placed at a considerable number of different manufacturers.

2 cm AA guns

The first contract that was placed was one at Oerlikon in Switzerland. It comprised an order for 450 off 2 cm light AA guns. Already in March 1939 the first batch arrived and these guns would be designated the 2 tl no.1. The extension "tl" - literally "tegen luchtdoelen" - meant "against airborne targets".

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Oerlikon 2 cm AA

The 2 tl guns [sometimes called heavy AA machineguns - we stick to the label of light AA guns] were very modern and reliable weapons against low flying planes. They were able to spray effective fire up to a mere 1,500 metres. The weapons were easy to operate and quite simple to aim. The aiming action was quickly learnt, not the least due to the fact that all small grenades fired had a tiny phosphorous load that ignited the moment the grenade was fired and made it easy to trace the volley to the aiming point.

Within six months 120 off Oerlikons were delivered. The invasion of Poland in 1939 caused a sudden stop to the delivery of the balance of the ordered guns. The ever increasing export and transit restrictions that European countries enforced caused the Swiss to decide to sanction further delivery. The Dutch quickly found alternative delivery at Scotti [full name: Scotti Isotta Fraschini] in Italy, which produced an Oerlikon derivate. Scotti received an order for 200 off their 2 cm gun type, which was obviously very similar to the Oerlikon. The first batch of 35 guns arrived in January 1940. No more would follow until the German invasion for also Italy would cease delivery, but totally unexpected at 14 May 1940 (!) another batch arrived. The arrived Scotti 2 cm guns were designated 2 tl no.2.

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Oerlikon 2 cm AA

All in all the Dutch received 155 off modern 2 cm light AA guns. All of these would be assigned to so called "Company AA machineguns", where the 2 cm guns were assigned in couples [2 piece platoons]. The organisation of these units is addressed later when the organisation of the Dutch air-to-ground command is described.

The Dutch navy also made use of 2 cm AA guns. The navy had chosen a very capable weapon that outmatched the Oerlikon in fire-rate. The Swiss Hispano Suiza 404 gun, which was designated as the "machinegun of 20 mm no.1". It was both used on board sea-planes [Dornier 24K], navy units and as a land based AA gun. Its fire-rate was double the rate of Oerlikon. It is unknown how many were delivered. It is certain that 30 off were ordered via British sources, which were all delivered. It is also a known fact that a number of AA units [at two sea-plane bases and at Den Helder] were equipped with these guns.

Since the specification of both the Oerlikon and the Scotti is almost identical we specify both weapons in one table.

  Gun 2 tl [20 mm] no.1 and no.2
Manufacturer: Oerlikon / Scotti
Calibre: 20 mm
Barrel-length: 1.400 mm [70 calibres]
Action: fully automatic
Gun weight [incl mounting]: 363 kg [incl. undercarriage]
291 kg [excl. undercarriage]
Elevation: 85° max.
Fire rate: 180 rounds per minute
Range: 1,800 metre [max.]
1.300 metre effective
Ammo: HE [240 gram] percussion fuse, with tracer
V0: 830 m/sec
Year of introduction: 1939
Mounting: pivoted base, removable two-wheel carriage
Number in service May 1940: 155 [5 were used for training]


4 cm AA guns

Already in 1936 the first tests were performed with the 4 cm Bofors AA gun. It was very well received but when the military purchasers approached Bofors for order placement they were refused at the door due to the fact that Bofors had no production slots open anymore. Still the inventive Dutch purchasers managed to procure 36 off these guns - produced under licence in Poland. The guns arrived in Holland in the summer of 1939. Later another 10 of these guns were received via Hungary, but then all sources dried up. The 46 guns formed 15 batteries of medium AAA, with three guns each.

Since the Dutch [also] realised that 2 cm and 4 cm guns would be the prime weapons for air-defence, they endeavoured to find alternative sources for their medium AA requirements. The Dutch ended up ordering another 20 guns in this range at Rheinmetall Borsig in Germany. The Germans had developed a 37 mm AA gun that was far more expensive than the Bofors guns. After delivery of three guns [without ammo] the German government blocked any further delivery to Holland. It surprises not ... Obviously the German guns were not used in May 1940.

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Collection of the main weapons of the AAA units (may 1940)

The Bofors guns were very easy to transport due to the fact that they were trailer mounted. This trailer could be fixed by means of four jack-up stamps on each corner of the carriage. Each battery was provided with a fire-directional control system, which proved to be of moderate quality. The guns themselves were equipped with Coertz-corrector aiming devices [light projectory system].

After the capitulation the Germans used the captured guns themselves and designated these 4.0 cm Flak 28 (h).

The navy had quite a number of vessels equipped with designated medium AA batteries on board, which were single or twin mounted Bofors 40 mm guns. Hazemeyer had designed a formidable fire-control for these batteries based on a Dutch-German design of tachymetry. The American navy copied this system during WWII. The batteries were trimmed by means of three independently moving axes, which caused the gun-base to remain stable on a moving ship.  

  Gun 4 tl [40 mm]
Manufacturer: Bofors [Polish and Hungarian licence]
Calibre: 40 mm
Barrel-length: 2.400 mm [60 calibres]
Action: fully automatic
Gun weight [incl mounting]: 1.950 kg [incl. undercarriage]
Elevation: 90° max.
Fire rate: 130 rounds per minute
Range: 4,200 metre [max.]
2.800 metre effective
Ammo: HE [1 kg] timer fuse
V0: 850 m/sec
Year of introduction: 1940
Mounting: pivoted base, 4 leg spread fixed four-wheel carriage
Number in service May 1940: 46 [4 were used for training]


7.5 cm AA guns

In 1935 the first [of sixteen] modern AAA batteries were formed with Vickers 7.5 cm AA guns. These batteries comprised three guns plus a fire-directional computer. The introduction of this type of gun and fire-controls meant that a new era of technique was introduced to the Dutch air-defences. The Vickers guns fired rounds with pyrotechnical timer-fuses. This meant that detonation would occur when the projectile was the closest to its target. The considerable shrapnel cloud close to the plane would be devastating enough to cause heavy damage or destroy it. This device did however make an accurate fire-control imperative [otherwise the timed detonation would be too far off].

The Vickers fire control proved quite efficient. When general information - mostly coming from the range finder - such as height, distance, target speed, wind speed and target direction was entered into the [mechanical] computer it calculated the exact angle of fire and the setting of the grenade timer. The computer sent an electrical signal to all three guns [e.g. the instruments of the gun] after which the default settings would have to be met by adjusting the gun to a matching scale-setting. Meanwhile the grenade timer had been set according to the calculated time. If the gun crew managed to aim the gun soon enough and the grenade was set and loaded in time, the battery fire could proof very efficient. Disadvantage of the Vickers control system was that it did not include a mode in which the barrel-wear [from frequent use] could be incorporated in the calculation. Since the first hours of the invasion caused the batteries to be continuously in action, the barrel wear soon became an element of significance. Smart battery commanders were able to adjust the calculation outputs by instructing the gun-crews to incorporate a certain variable. As such the batteries were often able to overcome the increasing error in the settings and continue to produce effective fire. Another disadvantage of the fire-controls was that within a room of 1.000 metres the calculations were useless due to the fact that the gun-action would be unable to match the instrument outcome. The time between production of the calculation and the gun adjustment was too long to produce accurate gun adjustment and as such accurate fire. As such all heavy AAA batteries were also equipped with two or four heavy machineguns in order to have some protection against low flying enemy planes.

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The Vickers 7.5 cm AA gun (may 1940)

After the first batch of 48 guns had been procured and phased in the AAA units, it was soon decided that the very capable guns were required in larger quantity in order to be able to protect the Dutch skies against planes flying at mediocre altitude [up to 6,000 metres]. It was decided that the Dutch national defence industry [Artillerie Inrichtingen Hembrug] would produce the guns in license and that the Dutch company Hazemeyer would design and manufacture an improved fire-control computer. As off the summer of 1939 the Hembrug produced 9 guns [3 batteries] on a monthly basis. In May 1940 about 90 guns had been produced, but two unfortunate events struck the project. First of all the Hembrug experienced great difficulty in producing reliable pyrotechnical time-fuses. Secondly the chief-engineer of the Hazemeyer company grew seriously ill and was unable to finish the new fire-control computer. It caused 90 guns to be stored unemployed in the arsenals when the hostilities broke out. Meanwhile the Dutch managed to still mobilize another eight batteries with the Dutch licence built guns and equip these with older fire-controls of the 6tl and 7tl batteries. These would however prove very unreliable in action. The end of the story was even more unfortunate. The Germans seized the 90 stored guns [and many of the guns from mobilized units] and would later use them [in Holland and elsewhere in the occupied territory] themselves and designated these 7.5 cm Flak M 35 (h).

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Vickers battery stereoscope

Facing the hick-ups with the indigenous production, the Dutch looked for solutions abroad. One solution seemed to pay off, when in the winter of 1939/1940 60 off Skoda 7.5 cm guns were ordered via Germany [Czech manufacturer Skoda was under German control since the annexation]. After three batteries had been delivered [9 guns] the German government prevented further delivery. All three batteries would however successfully take aim at their deliverers during the May War.

The Vickers [and licence] produced guns were designated 7.5 tl no.1; the Skoda guns were known under the type name 7.5 tl no.2. At 10 May 1940 no more than 81 off guns were mobilized in 27 operational units. 

  Gun 7.5 tl [75 mm] Vickers / Skoda  
Manufacturer: Vickers Armstrong / Skoda  
Calibre: 75 mm
Barrel-length: 3.000 mm [40 calibres] / 3.652 mm [49 kalibers]
Action: half-automatic
Gun weight [incl mounting]: 3.280 kg / 4.200 kg [incl. undercarriage]
2.791 kg / 2.800 kg [excl. undercarriage]
Elevation: 90° / 85° max.
Fire rate: 25 rounds per minute
Range: 8,000 metre [max.], 6.000 metre effective
Ammo: HE [6.5 kg] timer fuse
V0: 850 m/sec
Year of introduction: 1935 / 1940
Mounting: pivoted base, 4 leg spread fixed
Number in service May 1940: 72 / 9


Heavy machineguns

The Dutch had formed 65 off AA machinegun platoons [452 MG's in total] in order to protect strategic points against low flying planes. After WWI the Dutch had captured many German Spandau M08 machineguns when German troops fled over Dutch soil in October and November 1918. These machineguns were designated M.25. These weapons were later all applied for AA duty.

Basically all AA units were equipped with two or more of these MG's. The standard AA MG platoon comprised four M.25's. AA MG Companies usually comprised four platoons and one battery; one platoon with four 2 tl guns and two MG's, three platoons with two 2 tl guns and two MG's and one battery with three 4 tl guns. Also 6 tl, 7 tl and 7.5 tl batteries had two MG's for low flying targets.

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The standard AA machine gun, the Spandau M.08 [Dutch M.25] (may 1940)

The Spandau machineguns were [generally spoken] quite unreliable. Although the Spandau had proven itself an excellent weapon during WWI, the captured weapons were often worn out by frequent use by their first owners. In May 1940 a major portion of the arsenal proved unfit for action; some MG's didn't even fire a single shot due to mechanical malfunction. There is one known report of a platoon where all four MG's refused when they had to open fire ...

Also the standard army heavy machinegun [Schwarzlose] was easily prepared for AA duty. An extendable tripod was available to all MG platoons so that the MG could be applied for AA duty.  

The navy units had quite a number of single or twin mounted water cooled 12.7 mm machineguns on board of almost all surface units [similar to the well known pom-pom].

The Coast artillery had been ditributed with Vickers MG's for light AA duties. Usually two MG's per battery.  

Search lights

The Dutch army had quite a variety of search lights in use at the eve of war. Basically three main types were in use: 75/90 cm mirror diameter, 110/120 cm and 150 cm. These search lights were used in groups of three or four, which was called a section. Three, four or five sections together formed a division of searchlights.

The 150 cm [=diameter of the mirror] lights were the most modern and these were capable of reaching 4,000 metre heights for effective lighting of planes. The older smaller lights with less intensive lamps were only capable of 2.500 - 3.000 metre. All searchlights were fitted on top of trailers and powered by generators. Also, every section had an acoustic apparatus as a directional finder. This very basic instrument [it looked like a huge metal ear] had a reach of about 4,000 metre. It hardly ever worked properly. And if it did the speed of modern planes often made it obsolete.

The most powerful searchlight was the probing light in each section. Upon its successful locking a plane in its light bundle, the others would join after which the probing light would start looking for new targets. The section-commander was always positioned close to the probing search-light. He had a night vision binoculars at his disposal, and as such he was able to spot planes with very little light available. As such he could direct the probing light to a spotted target.

The disposition of one section of search lights was usually in a square box [or triangle if only three lights were available] with each leg measuring 2 tot 3 km. Between each light position telephone-contact was maintained in order to coordinate operation. Also coordination with the heavy or medium AAA units in the direct vicinity was maintained by means of telephones.

The poorly equipped Dutch army was in the process of modernization and as such two prototypes of modern radar had been constructed that produced very promising results. The prototypes [designer was engineer J. von Weiler] proved to be able to trace planes up to a distance of 15 km. The intention was to procure 200 of these machines for the AA defences. Interesting detail is that the subject engineer managed to escape to England with both prototypes and that his invention proved to be even better than the English radar at that point.

Altogether 164 searchlights [42 sections] were in use at the eve of battle. They would hardly be used due to the fact that the AAA batteries had received instructions not to fire during night hours. This instruction was a direct result of the shortage of ammo, and therefore intention was to only waist ammo on prime targets with clear daylight vision.

Dislocation of weapons and devices

From the military study to the airforce during the May War, we have taken the below listed overview of dislocation of all air-to-ground defence units at 10 May 1940.

  Commando     10 tl     7.5 tl     7 tl     6 tl     4 tl     2 tl     M.25     SL  
Amsterdam area:   15 9   3 23 72 48
Rotterdam / The Hague area:   36     6 29 108 70
Utrecht / Soesterberg area:   15   21   4 148 24
Field Army:         21 70 56  
1st Corps:         6 16 12  
Fortress Den Helder: 3 9       2 26 12
TC Zeeland:   3 3   3   20 4
Bergen area:   3     3 3 4 6
TC Limburg:     3       6  
TC Friesland:           3    
3 81 12 21 42 150 452 164
Source: Military Study to the Dutch air-defences in May 1940 - F.J. Molenaar (1970)


Organisation of the Dutch army ground-to-air defences in May 1940

In November 1938 the Air-defence Command was formed. It was commanded by Major-General Best [who indeed proved to be one of the best, later promoted to Lieutenant-General] and comprised the air-force, the air-to-ground defences, the search light divisions and the air-defence volunteer corps. Shortly before the invasion the airbase defences were entirely brought under the supervision of the Air Defence Command.

Let us first elaborate on the different branches within this command. The air-force and air-to-ground defences speak for themselves. The search light division was in fact an engineer branch of the army. The 3rd Regiment Engineers formed this division and they manned all search light units. The most complex branch however was the huge volunteer [auxilary] corps.

The volunteer corps comprised two different sub-branches: the voluntary AAA corps and the voluntary air watch corps. The first one mentioned was manning all AA weapons that had been procured by private funding. That were 2.tl guns only. Due to limited governmental funding for new AA weapons, the Dutch government had invited major industries and companies to invest money in the protection of their own premises by procuring AA weapons themselves. The military purchasers took care of the contracts, but the guns would be assigned to the protection of the funders' premises [although under military command]. As such numerous guns were indeed bought from private funds and manned by semi-military personnel. The personnel came under military authority and were assigned to the volunteer corps.

The other volunteer sub-branch was the air watch corps. This corps manned the numerous [hundreds] watch posts all over the country that were constructed [or modified] as warning and monitoring positions for enemy plane moves. Usually high towers, church-towers or other high buildings available in villages and towns were used or dedicated elevated posts were constructed. These positions were manned by volunteers that were dressed as military personnel but in fact were semi-military volunteers. These men also manned the much extended radio network. This network worked in circles. The country was divided in areas that were given shape by means of closed radio network circles to which each individual station was connected. These circles all interconnected, and as such radio warnings could be shared with all circles within no time. All other units of the air-defence made use of this vast radio network to be updated about approaching planes. It worked perfectly, also during the war days.

Three area air-defence commands [Amsterdam, Rotterdam/The Hague, Utrecht/Soesterberg] had been created. These were initially all reporting to the Commander of the Air Defences [Best], but later [April 1940] the Utrecht/Soesterberg sector was placed directly under the Commander Field Army [due to the fact that practically all AA units defended defence-line areas manned by the Field Army]. The air-defence commands had a dedicated task in securing the air-defences of all vital and strategic landmarks in their respective regions. The volunteer corps units that fell within the three regions of the air-defence commands all reported to the central air-defence command directly.

Also the airbase commanders [commanding a part of the ground troops and air-force units] in the west reported to the Commander Air-Defences.

We already saw that the Commander Field Army had authority over one air-defence command [Utrecht/Soesterberg]. He also commanded a small branch of dedicated Field Army Air-Defences which was completely dedicated to Field Army purposes. Furthermore he was the chief commander of one regiment of the air-force [2nd Air Force Regiment] that mainly comprised reconnaissance and artillery-observation planes. Just one fighter squadron was part of this regiment. Expansion of the Field Army airforce was foreseen, to start with the 26 G-1 Wasp planes that were in the process of being modified, but of which only three were in service on 10 May 1940 (and a few more during the war days). A few hours after the invasion the 2nd AF Regiment would be reassigned under the Commander Air Defences.

The flying navy units fell under navy command and were as such operating independently of the air-defence command. Besides a modest number of modern Fokker T-VIII-w seaplanes, the entire Navy Air Corps in the Netherlands comprised old bi-plane types, which were useless in combat.

All in all quiet a complex command structure that would even change once again after the Germans had invaded the country. Only hours after the invasion started the entire airforce command was put under direct supervision of the General Headquarters. All missions by the airforce had to be sanctioned by the CIC and his direct aids-de-camp from that moment on. That did not turn out to be operationally effective.

Battle results

The combined Dutch air-defences and ground forces proved to be highly effective against the massive German air armada that was sent into battle over Holland. In total over 525 crashed or emergency landed German planes have been accounted for during the entire May War in 1940. This figure does however require further elaboration.

First of all: it is impossible to give hard facts and figures about how many planes were either downed or destroyed [or heavily damaged] by which weapon or unit. Figures mentioned are estimates based on the best possible analysis.

Lieutenant-Colonel E.H. Brongers [ret.] has studied [for many decades] on an inventory of all German planes that were reported missing or crashed over Holland during the period 10-18 May 1940. This extensive list shows over 525 planes and is a result of thorough study and analysis of actual crashes, reported crashes, German loss directories and Dutch sources. Through the years many reported events have been crossed out from the list due to ill proof or duplication. Today the list may be considered highly reliable. It shows a mere 530 individual German losses.

The loss of German transport planes of the Ju-52 type was staggering. This very slow and vulnerable plane had been assigned a very hard and risky task of shuttling in the entire German airlanding and airborne army. In total 450 planes were used during the first waves, later reinforced by unknown numbers from Lufwaffe schools and units previously assigned elsewhere. Especially the first wave suffered tremendously from Dutch AAA units and ground fire at the assaulted AFB's as well as of poor landing facilities or bad landing grounds. The follow-up waves had increased their approaching altitude causing the Dutch light AA units to remain merely unemployed. The Kampfgruppe zur besondere Verwendung 2 alone lost 73% of its strength according to German figures, which equals a loss of 140 planes.

The second and later waves of transporters suffered less from AA fire, but on the other hand they suffered more from blocked landings strips because meanwhile all previous landings - with exception of the ones at Waalhaven - had failed or blocked the runways. As such many planes had to divert to alternate landing grounds which were either blocked by means of barricades / barriers or simply unsuitable for landing. This caused the Germans to lose many planes that were not lost by direct Dutch doing. Of these planes that made forced landings many sustained light or medium damage and as a consequence these ones were often repaired later. For example, Fokker repaired 50-100 Ju-52 in the year 1940 still.

Of the 530 planes on the list probably about 200-250 were recovered and repaired, or used to assemble new planes from re-usable parts. The actual German loss should therefore be brought back to about 275-325 planes at 31 December 1940 [we say December 1940 because the majority of damaged planes had been repaired prior to this date]. The German figures state 231 planes were total write-offs eventually. This figure is probably fractions too low, but it proofs that losses had been high.

The battle reports from the AA units that saw action in May 1940 [almost all came in action] state exaggerated numbers of downed planes. This was caused by a great number of reasons, but the most common was the joint claim of many units for one and the same plane. Also, planes that showed any form of damage, for example smoke trails or rumbling engines, were often reported as downed or destroyed whereas it was far from certain whether they still made it home. It is all common practise that claims are hardly ever too low. It is hard to predict which share of the German loss was accountable to the Dutch AA units. An estimate would be nothing less than a wild gestimate and therefore we shall refrain from giving any figure.

It is however safe to say that the relatively few AA units the Dutch could mobilize in May 1940 had a field day on the first day of the war. The modern AA units booked plenty of successes, especially around the zones where the airlanding operation took place. The west of Holland was soon scattered with wreckages of German planes. Also the units along the Waal river - near and in the Betuwe region - shot down a considerable number of German planes. The machinegun platoons proved almost worthless, and so did the 6 tl units. Almost all other AA batteries and platoons were able to score one or more confirmed kills.

The Dutch airforce shot down a considerable number of German planes. Exact figures are unknown, but between 30 and 35 planes were shot down as a consequence of aerial combat. This number is higher than the number of Dutch planes lost during air-combat.

The German loss of planes was in many ways easy to overcome, but the loss of more than half their transport fleet would remain a burden throughout the war. In 1941 when the invasion of Crete was launched, the loss of transport planes had nearly been compensated by new deliveries when yet again over Crete a heavy loss was suffered. It would all lead to devastating effects when Operation Barbarossa turned out to grow into a war of attrition. This was the moment the transport fleet was needed more than ever, and the great shortage of transport planes was especially hard felt then ...

Also - the Dutch managed to capture many well trained air-crews from the crashed and landed planes in the west. Amongst the 1.350 POW's that were later [13 and 14 May] shipped to England, many hundreds were highly trained Luftwaffe personnel that were harder to replace than the lost planes. Most hard felt losses were the scores of Luftwaffe instructors that had been assigned to the KGzbV2 formations due to severe shortages of transport pilots. Their loss was hard to compensate, obviously.

It is unknown how many men of the Luftwaffe actually perished due to Dutch doing, but the most reliable German registry provides us with 198 names of aircrew that were killed in combat in the period 10-18 May 1940 over Holland.

Dutch losses

The Dutch air defences also paid a price themselves. The airforce lost 75 men [aircrew and dedicated ground crew]. The AAA units lost 45 men, the search light division 6 men, the volunteer corps 7 men and the regular air defence troops 58 men. Altogether a very modest loss in comparison to the damage and loss inflicted on the enemy.

The Dutch airforce lost the majority of its planes due to bombardment, fighter strafing, unenforced crash landing or demolishment. Of the 145 planes available at 10 May, two third had been lost at 14 May when the capitulation was declared.