The Grebbeline at Rhenen
The previous chapter described the basic lay-out of the Grebbeline defence structure, with some specific details about the defences around Rhenen [the Grebbeberg]. We shall now address the important specifics regarding troops and units.
The southern sector of the Grebbeline was defended by the units of the 2nd Corps of the Field Army. This Corps consisted of the 2nd and 4th Division and corps troops, like long range artillery, pioneers, medical troops and others. About 25,000 men altogether. The 4th Division defended the sector between the Rhine and Achterberg. In fact a narrow stretch of land, but necessary to be defended by relatively large forces due to the absent inundations between Rhenen and Wageningen.
The 4th Division comprised two infantry regiments [8.RI and 19.RI], two additional heavy machinegun companies, two additional AT units, three artillerie battalions [24 x 7,5; 12 x 15 cm] and additional support and army support units. About 10,000 men in total.
The divisional sector was divided into a northern and a southern regimental sector. The northern sector [Achterberg] was defended by the bulk of 19.RI and the southern sector [Grebbeberg] by 8.RI. Both regiments had their troops deployed over all three defence lines.
Next to the three artillery battalions of the 4th Division, comprising 36 guns, a number of artillery battalions of the 2nd Corps had been positioned in the 4th Division sector. It were mainly older guns that formed the Corps artillery. It were two batteries with 15 cm howitzers [Vickers] and three batteries of vintage 12,5 cm Krupp guns. The only modern component was formed by four batteries of the highly capable 10,5 cm Bofors guns, called '10-veld' in the Dutch army. These rapid-fire howitzer type guns were capable of delivering at a range of over 16 km. They were however designated for artillery counter fire and in depth barrages in the 2nd Division sector. But with a slight vector change these batteries were able to assist in the 4th Division sector too.
Also a battalion of 7,5 cm field artillery guns - that was positioned south of the Rhine [Betuwe] - was capable of delivering fire missions in front of the Grebbeberg.
The total maximum number of guns capable of supporting the Grebbeberg sector consisted of 36 guns 7,5 cm [range up to 10 km], 16 guns of 10,5 cm [range up to 16,5 km], 12 guns of 12,5 cm [range up to 8 km] and 24 howitzers of 15 cm [range up to 8,5 km]. Of these 88 guns only 60 were intended to give direct support to the 4th Division units. Since the width of the 4th Division sector was less than 5 km, and the main approach zone [e.g. the non-flooded area between Rhenen and Wageningen] had a width of less than 3 km, the number of artillery pieces available was more than adequate.
Every infantry regiment comprised a staff [about 125 men], an infantry-gun company [4 x 5,7 cm], a mortar company [6 x 8,1 cm], an AT company [6 x 4,7 cm] and three infantry battalions. Such a battalion had a staff [80 men], a heavy machinegun company with 12 Schwarzlose 7,9 mm heavy machineguns and three companies [180 men] with 12 light machineguns each. In other words, a battalion had 36 off light machineguns and 12 heavy machineguns. These numbers applied for the first twenty-four Regiments Infantry [RI]. The high numbered regiments had usually only 27 light and 8 heavy machineguns per battalion.
The heavy support weapons had been distributed among the defence positions, with emphasis on the front-line. Many of the heavy machineguns were fitted in pillboxes, and a small number of the light machineguns too. The AT and infantry guns had been distributed over the defences in single gun positions. The few mortars were positioned directly behind the stop-line.
Pillboxes and other fortifications
The Grebbeline had been fortified with numerous concrete and steel pillboxes. Basically all of these had been constructed in the frontline; only a few in an intermediate defence line behind that. All concrete and steel reinforcements were intended for AT guns or MG's, none for shelter purposes. The construction of concrete shelter and observation pillboxes was in the planning. In April 1940 a very ambitious plan - called 'de beton-plan' [lit: 'the concrete plan'] to fortify the Dutch main defences with improved pillboxes and vast amounts of concrete shelters and command-posts had been approved. Its realisation - obviously - came too late.
The steel cupola's, that were in use as heavy machinegun pillboxes, were excellent constructions. The thick cast iron casing was impregnable for any German weapon with exception of the notorious '88', that would not see action at the Grebbeberg. The only piece of the construction that could be inflicted was the weapon itself, that was packed in an armoured sleeve that prevented small arms and shrapnell damage to the barrel.
The concrete pillboxes, usually intended to shelter a machinegun position, were far less valuable. The design provided for a frontal loop-hole, flanked by two more angled loop-holes. The frontal loop-hole in particular was very vulnerable to enemy fire. These pillboxes formed the majority of the reinforced structures though and as such the average value of the pillboxes was quite modest if it came to intense or prolongued action, particularly when the light AT guns were deployed by the attackers.
The bulk of infantry men was depending on the basic dug-out trenches for its covered firing position. These trenches were very basic structures. They had the WWI shape, with usually the high rear profile [to prevent the visibility of soldiers against a differentiating background], the underground dug-outs, the framework timbering as well as the good old duck-boards [against trench feet]. Although the resistance against indirect fire was quite good, direct hits of calibres above 7,5 cm usually caused quite extensive structural damage. The linieair shape of these trenches was another vulnerable issue. The German practise to penetrate defences at a weak spot and subsequent outflanking of the adjecent systems, was all but hampered by the Dutch trench designs. Even the forward defences, which were in fact platoon size positions in the field with no interconnecting trenches to adjecent or rear positions, had been designed for a forward and only marginal flanking field of fire.
Although much trench work had been done during the mobilisation, much of the interconnecting trench system failed, even in the main defence area (frontline - stopline sector). That omission would seriously hamper logistics under fire. Another major omission was a subsidiary trench system behind both the front-line and stop-line main trenches. That caused a lacking availability of local tactical reserves right in the frontsectors and also caused the absence of facilities like first and second echelon ammo caches and first-aid posts. These flaws in the defence-engineering would seriously reduce the effectiveness of the defences at Rhenen and Achterberg.
Anti Aircraft Artillery
Anti aircraft artillery [AAA] and lighter AA weapons were much undersupplied. One battery of heavy AAA [Vickers] - with three 7,5 cm guns - formed the entire heavy AAA spectrum in the entire region.
Two platoons with two 2 cm Oerlikon guns and two heavy machineguns each were all that was available for this sector in regards to light AA weapons. One of the platoons was assigned as a guard to the sluice in front of the Grebbeberg, and the other was attached to the artillery positions on the eastside of the city of Rhenen. Other light AA weapons were located south of the Rhine, but again in very small numbers. For a vital defence sector like the Grebbeberg, that was a pathetic situation.
This modest anti-aircraft defence wouldn't scare a crow, let alone a professional airforce like the Luftwaffe. It was however the case that the AA defences in the Netherlands had been deliberately concentrated in the west of the country in order to protect the departmental city of the Hague, the capital Amsterdam, the harbour city Rotterdam and the important airfields in the west of the country. The AA defence density in the west of the country was quite acceptable, its presence amongst the field army units far below the necessary bare minimum.
Command and control
The 2nd Corps was part of the Field Army, that was commanded by Lieutenant-General J.J.G. (Baron) van Voorst tot Voorst. The Field Army staff - responsible for coordination and control of the entire Field Army - situated in the city of Zeist.
The 2nd Corps was commanded by Major-General Harberts, a die-hard General of the traditional kind. He intended to hold a firm grip on the Grebbeberg defences, because it was foreseen that the German offensive emphasis would lay at that very point. His headquarters were situated in the city of Doorn, well away from the front.
The 4th Division was commanded by Colonel van Loon. He had a large divisional headquarters about five km west of the Grebbeberg.
The 8th Infantry Regiment - that occupied the trenches on and in front of the Grebbeberg - was commanded by Lieutenant-Colonel Hennink, a traditional and capable officer. He had his commandpost situated on the west side of the Grebbeberg.
The C-8.RI had three battalion commanders. Two of these had their CP's to the rear of the stop-line, but the commander of the 3rd Battalion [Major Voigt] had his CP in the forward defences, where he personally commanded two of his three companies.
The artillery was commanded by two chiefs. There was the Divisional Artillery Commander [DAC] - who basically ruled all three divisional artillery battalions - and the Army Corps Artillery Commander [LKAC] - who had all the Armee Corps artillery units under his authority. The LKAC was the most senior ranked officer of the two and authorized to superseed the DAC. All field commanders had to request fire-missions by climbing the chain of command. The company-commander contacted the battalion-commander, the latter contacted the regiment commander and the regiment commander filed his request at the DAC or LKAC. Needless to say that this viscious procedure was all but adequate for imminently required fire support. Also, autonomy of artillery commanders to open fire on their own initiatives had been choked to the very level of urgent self-defence. This restriction was not only due to the strict hierachy that dominated the Dutch armed forces, but also derived from a fear of spilling precious ammo.
Finally, a word about the communication. The distribution of wireless sets had been limited to some of the artillery battalions. Only a handful of forward artillery observers were in possession of such a wireless set. In fact only two were available at the Grebbeberg. The balance of transmissions was done by hard-wired telephone-lines. And even those devices were relatively rare. Basically all company CP's were hard-wire connected to the battalion CP's (and beyond). But the hard-wire connections to the platoon- and squad levels were often missing, except for most of the bunkers, which were virtually all hot wired to the CP's. Moreover the wired connections had often been laid on the top-soil or even hung in trees or nailed onto poles. Ground cable or dug-in cable had not been used, mainly because of the fear of environmental claims [the Grebbeberg area was 'a pearl of nature']. It was generally accepted that the first enemy artillery barrage would probably shatter most communication lines.
As an alternative to the radio and telephone connections there were the old school devices like the buggle, the optical instruments and last but not least the messengers. There were the scarce flare pistols and the company buggles, as well as here and there the optical instruments (lamps). But for longer distances or covered positions the good old messenger remained highly important. Obviously the messenger option would have its known disadvantages, like the time consumption issue, the vulnerability of the messenger himself and the fact that under fire messenger communications were the first to stall.
The Grebbeberg was a remarkable elevation in the landscape, especially when one approaches the area from the east. It was one of the remains of the last Great Ice Age, that had pushed the land ahead of the ice. The main road between Rhenen and Wageningen made a steep curve in front of the Grebbeberg, where it negotiated its way in between the old bastions of the ancient defences, crossed the narrow river Grebbe and than curved its way through and up the Grebbeberg itself, to end on the west side of the steep hill in the little village Rhenen.
The forward positions - manned by a strength of little over two companies supported by some heavy machineguns and a few 5,7 cm guns - were situated in the flat area between the Grebbeberg and the city of Wageningen. The entire area - called the Nude - was covered with groove, orchards and other tree formations with some open spaces between them. The fields of fire had not been cleared of obstacles whatsoever. That had been considered too expensive ...
The elevated bastions in front of the bridge [annex sluice] over the Grebbe, had been reinstated as fortifications after centuries of decade. The three main bastions [called 'Hoornwerk', after the original designer Menno van Coehoorn] formed the main part of the front-line east of the Grebbeberg itself. The bastions had been reinforced with quite a number of casemates and an extensive pattern of trenches. The three bastions were divided by the main road [Rhenen - Wageningen] and the main causeway coming from the Rhine shore and leading towards the sluice. The field of fire from the bastions was extremely poor. Only the central bastion had an open field of fire, but the left bastion had a much extended orchard on its left flank leading almost up to its roots, facilitating an enemy to approach virtually undetected. The field of fire from the right bastion was seriously hampered by the main causeway that left a large dead angle in the terrain. Moreover, all firing positions on the elevated bastions, which were situated behind a three metre wide water-filled ditch, were situated on top level. Only narrow sight-holes had been constructed to monitor the direct approaches of the bastions, but those positions were obviously extremely danger to man under fire. Last but not least was the entire open terrain east of the bastions intersected by several (nearly) dry irrigation ditches that made right angles with the defences. These ditches were hardly covered by weapon points. The the bastions - which had four concrete casemates as the only additional reinforcements besides earth dug-outs - contained only four platoons of infantry.
Behind these bastions, just west of the narrow river, the Grebbeberg made a steep climb [60 m]. On the ridge a series of steel cupola's had been constructed that contained heavy machineguns. These positions covered the approach area of the Hoornwerk defences. The minimum angle of MG's in these cupola's was however such that the field of fire was limited to the area east of the bastions.
With exception of the Hoornwerk sector, the frontline was situated on the westbank of the river Grebbe. Since the river streames slightly east by northeast, the distance between the front- and stopline increased north of the Grebbeberg to even beyond 1,000 m. In order to fill the occuring gap a limited intermediate defence was constructed from the north of the Grebbeberg to the southside of the inundation at Achterberg.
The stopline ran straight across the centre of the Grebbeberg, from the Rhine towards the north, where it transferred into a ground level trench that continued into Achterberg. The Grebbeberg itself was mainly covered with young trees, with a few open fields and two soccer pitches as well as a large zoo, which was situated on the top of the Grebbeberg and on the northwest side. The wild animals in the zoo had been moved or killed [at the 10th of May].
On the westside of the Grebbeberg lay the village of Rhenen. The Grebbeberg and the village were seperated by a sunken railway track, about 15 m below ground-level. This track ran from the Betuwe - south of the Rhine - to the north. It crossed the Rhine over a large bridge. The sunken railway was an excellent tank obstacle and only a viaduct nearby the station provided for a cross-over. North of the Grebbeberg the railway track came level again, where it subsequently transferred into an elevated railway well above ground level at Achterberg. Two narrow tunnels under the track kept the plain in between the Grebbeberg and Achterberg accessable.
West and north of Rhenen extensive forests provided excellent cover for artillery positions. Most of the heavy artillery was placed in that area. Some batteries had been positioned on elevated grounds in the village itself and two artillery battalions had been placed on the west side of the Grebbeberg.
The Grebbeline defences in the most southern sector between Achterberg and the Grebbeberg were formed by the regiments 8.RI and 19.RI, backed up by 60 artillery pieces and some additional reinforcements. The total strength of the two regiments, divisional support units and artillery units added up to beyond 11,000 men.
These 11,000 men were not by far deployed in the front area's. Respectively 400, 1.250 and 750 men infantry had been divided over the forward positions, front- and stopline in the direct Grebbeberg sector. That was no more than 2,500 men altogether. About the same number applied to the adjecent Achterberg sector, with exception of the almost absent forward defences there.
These less than 5,000 men infantry in the actual trenches were supported by another say 500 men supporting units like heavy machinegun platoons and AT gun crews. In other words, about half the sector strength of 11,000 men was actually deployed in the trenches, whereas the other half was stationed further to the rear occupied with either support duties or as reserves. Should one focus on the frontline, that after all had to rebuff the main offensive, only about 2,500 men occupied the trenches in the total divisional sector. That was less than one man every metre. The trenches had such low containment capacity - and lacked a subsidiairy system to contain first-line reserves, that those 2.500 men were about the maximum capacity that could be deployed. Since an attacker would always concentrate his forces, and as such gain an important local superior strength, these defence figures betray the relative strength of the defences.