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The north


In the evening of the 11th the first German units had reached the area east of the Wonsline. This weak defence line - originally intended as an assembly trench for the retreated troops from the east - was not much more than a mere 10 kilometre long entrenched single line screen around the dike-head, containing no traverses or communication trenches and hardly any in depth defences. It was named after a village that was situated in the centre of the line, Wons. It was hardly fortified. Plans for concrete reinforcements had still been in process when the invasion occurred. The lacking concrete and steel reinforcements caused the Wonsline to be an entirely traditional single line trench merely consisting out of trenches, hide outs and sand/timber constructed weapon points. The number of support weapons for the infantry was low, artillery was absent. It had been considered that navy units could support with their main guns, but the navy was much aware that such would soon attract the Luftwaffe.   

Wonsline in focus

The Wonsline in the province Friesland [Frisia] was an arc-shaped thin screen of field erected trenches. The high groundwater-level prevented dug-out trench construction. The negative consequence of the elevated defensive reinforcements in the open field is obvious: visibility and vulnerability. The southern extremity of the line was seen at the small harbour city Makkum. In a bulge shape the line ran via the village Wons (after which it was called) to the north at the Dutch village Zurich (Zurig). The Zurich area was the only stretch that lacked inundations in front of the defences.

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The Wonsline and Kornwerderzand at 12 and 13 May (may 1940)

Four main roads intersected with the trench-line and were - as such- potential main approach routes for the opponent. Three of the four of these roads were situated in the heart of the line. One at Wons and two at the slightly more northern village Hajum. One of the two roads at Hajum was the main traffic way that led to the Afsluitdijk. The distance between the land-head at the Afsluitdijk and the villages Wons and Hajum was 4 km respectively 3 km. The entire defence system had a length of 11 km, with some forward positions and a small force at the land-head Afsluitdijk excluded.  

The few strongholds in the Wonsline were erected from sandbags, clay and timber. These "man traps" were absolutely no match for modern field artillery and aerial bombardments. Overnight [11 / 12 May] landmines were laid at three locations: east of Zurich, Hajum and Wons.

The Wonsline was defended by one battalion, I-33.RI, a border infantry company [9.GC] and a depot infantry company. The battalion was made up out of elder reservists - most of them from native Frisian soil - under Major Smid, who was also commander of the entire defence line. The battalion had been reinforced by some of the men that had retreated from the east. Those troops were mainly from 1-12.GB [1st Company of 12th Border Infantry] with three heavy machineguns and three 4,7 cm AT guns. Also some navy troops came to aid. The local commander lacked any artillery or AAA.

In total the Wonsline contained a force of five infantry companies and some fragments of other units. Seven 4,7 cm AT guns, four 5,7 cm infantry guns and four navy guns of 3,7 cm [three at the land-head Afsluitdijk, one at Zurich] could support the infantry. In total about 800-900 men and 15 light guns.

The defence-line had a modest task in the Dutch strategy. Basically it was only intended to form an assembly line able to gather withdrawn troops from the northeast, assemble and reorganise them around Wons and send them on to the relative safety of the western part of the country. The formidable fortress on the dike was considered strong enough to withstand any enemy land-attack. It was however considered later that the Wons trenches could also function as a first line defence and as such the Wonsline was born. 

The defences in Friesland were commanded by the commander of Fortress Den Helder [main naval port], Rear-Admiral Jolles. Both the commander Wonsline and Fortress Kornwerderzand reported to the Rear-Admiral.

Opposing force

The Germans had deployed three cavalry regiments against the Wonsline. Only some squadrons would actually be involved in the forthcoming battle though.

The regiments were supported by four batteries of light field artillery [7,5 cm] and some light FLAK. The regiments themselves had 7,5 cm infantry guns, 3,7 cm AT guns and the organic mortars and MG's.

Events in the Wons-line

In the morning of the 12th the Dutch witnessed German troops preparing battle positions northeast of Hajum, at the village Pingjum [about 5 km from the land-head of the Afsluitdijk]. German reconnaissance patrols were reported in all three sectors.

In the early morning an armoured recce patrol of the German cavalry division undertook a recon mission to the most southern extremity of the line, near Makkum. They were able to get quite close to the Dutch positions without being spotted. The inundations did however hinder them so much that they decided to return. As they were just about to do so, a Dutch reconnaissance plane appeared overhead which forced the Germans to take cover. A sudden move that was spotted by the Dutch defenders who fired some volleys to the German team. No assault would follow in this sector anymore.

In the north at around 0700 hours German artillery was being positioned near the main-road east of the line. Immediately the defenders aimed their weapons on the German artillery positions after which the Germans rapidly retreated. Some time after, another attempt of the Germans to position guns in this area was again countered by Dutch fire. Then the Luftwaffe intervened. A squadron of Bf-109 fighters strafed the infantry trenches with enfilading fire, time and again. One of the planes [Bf-109E of 6./TrGr.186] was shot down by MG fire and crashed into the ground at Pingjum, boosting the Dutch moral. Two planes from the same unit were shot down over the Afsluitdijk and Den Helder around the same time.

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Dutch equipment driven into the Waddenzee (may 1940)

With the German planes still buzzing through the skies over the Wonsline, the German artillery started joining the concert of death. A barrage with 7,5 cm light field artillery was concentrated around the Wons area.

The Germans decided to try penetrating the line north of the village of Wons, where an access between two inundations provided for a narrow passage. After the barrage ended the assault was unleashed [1200 hours]. Supported by stand-by batteries and a considerable number of mortars and infantry guns the Germans went forward. The Dutch foward positions [manned by 9.GC] soon gave in, but the main defence didn't. 

The Dutch were able to oppose the Germans with assistance of two AT guns, one infantry gun and eleven heavy machine guns. One hour later the attack came to a complete stand-still. The first forward defences had been taken, but the main defence had produced such a dense fire, that the Germans were completely suppressed, unable to move forward or backward. The attackers remained pinned down for more than two hours. Also a German force east of Wons was pinned-down. At that location eight heavy machine guns and a light field gun contributed to the defence and with success. German artillery, boldly placed in a forward position in order to support with direct fire, was driven off and an intense machine gun fire was laid over the main-road. It was to no avail. The Germans brought in the artillery again and started pounding the village to rubble. The telephone lines were destroyed and some casemates got direct hits also demolishing two of the rare anti-tank guns. Nevertheless the defenders were still able to stood ground!

Then bad luck struck the defenders. Simple misunderstandings between two separate command posts combined with a series of German direct hits on weapon points led to a retreat of some sections in the defence-line. They fled towards the Afsluitdijk, meanwhile being treated on the combination of an aerial strafing raid and a persuing bombardment by artillery. At some positions the defenders were able to withhold the enemy in front for some time still, but Germans who had penetrated the defences elsewhere rapidly appeared in the rear of the remaining Dutch posts. Many had to surrender, only a handful succeeded in retreating in one piece to the rear.

The troops that had reached the dike were ordered to cross it to the west. The bridge in the dike had been blown up, thus preventing the Germans of crossing it by surprise whilst pursuing the retreating defenders. It would now all be up to the fortress and its 225 men!

The battle in the Wonsline demanded 16 Dutch KIA [including two civilian drivers]. On the day before already three men had been killed too, but not by German doing. A Sergeant-Major had lost it, shot two men and was then shot himself.

The German registred losses were very modest with 2 KIA (and another two probables). The figures show that the battle had not been of epic proportion. Nevertheless, the Germans had spent hours to get through the thin defences.  

Maritime events

In the morning of the 12th some Germans units of the 1st Cavalry Divisions were active around the coastal city of Stavoren. On the 11th it was already described that they had the intention to requisition some shipping room in order to cross the wide IJsselmeer [15 km minimum crossing distance].

The Dutch navy units crossing along the coast did scare many of the German cavalry men, not the least because they were all but maritime warriors. The Dutch naval command in Den Helder decided to reinforce the small flotilla on the IJsselmeer with two large mine-sweepers, which were fitted with 2 cm and 3,7 cm guns.

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Gunboat HrMs Brinio (may 1940)

The gunboat Hr Ms Friso returned to the area off the coast of Stavoren around 0930 hours. Its commander spotted German preparations for artillery and machine gun positions. Also he noticed that one of the few remaining [floating] vessels was pouring smoke suggesting a pending departure. He didn't hesitate and gave his gun-crews order to prepare a barrage on the Germans and the ship. Two miles offshore the gunboat [4 x 10,5 cm guns] started pounding the moored ship. The ship was a sitting duck and was soon put out of action.

Meanwhile the German guns [a battery of 7,5 cm] had started to respond to the Dutch naval fire. The artillery-commander on board the HrMs Friso easily measured the German positions, followed by intensive shelling of the German positions. One of the first rounds was a direct hit and the huge explosion of a German gun and its ammunition was a proof to the constables on board the HrMs Friso that their aim had been accurate. After firing more than a hundred rounds on the enemy, the vessel turned by and disappeared.

The Germans had however called on the Luftwaffe for assistance and on her way back for replenishment, Hr Ms Friso was attacked by four bombers. After some in vain German attempts, where all bombs went astray, a direct hit crippled and finally sunk the HrMs Friso. The brave ship capsized, taking three men [including one officer] with it into the deep. Both mine-sweepers nearby assisted in picking-up the survivors.

Another flight of dive bombers attacked the [close to the Afsluitdijk] moored gunboat HrMs Brinio, which was just about to return to the direction of Stavoren. The boat crew received the Germans with a fierce fire from the anti-aircraft machineguns and escaped destruction. Nevertheless shrapnel caused some leaks in the hull and the need for repairs was imperative. The ship had to dock, but would be ready for action early next day.


The Germans organised a quick recon patrol in the evening of the 12th to probe the Fortress Kornwerderzand defences. The Fortress was situated about 4 clicks off shore on the Afsluitdijk and only approachable (by land) by crossing the long flat and open causeway.

The Fortress occupation was ready for things to come and when the Germans tried to kill the search-lights of the Fortress with rifle fire, they were treated on heavy machinegun fire. Not this fire but landmines killed two of the Germans. Forced into cover they had overlooked the minefields in front of the forward defences and paid with their lives.