The battles of the Grebbeberg and the Afsluitdijk

On the evening of 13 May 1940, after three days of fighting, the Dutch 4th Infantry Division fled from the Grebbeberg, a wooded hill above the Rhine near the small town of Rhenen. The fall of this sector sealed the fate of the whole Grebbe Line, the main defensive position of the Dutch army, and forced its command to make a night withdrawal to the eastern front of the so-called Fortress Holland. In the same days, some 150 kilometres to the north, the garrison of the Kornwerderzand fortifications at the eastern end of the Afsluitdijk repulsed every German attempt to get across, and on 14 May a Dutch warship forced the German artillery to pull back. The two battles show the two faces of the five-day Dutch campaign: where the defence rested on weak, unfinished positions and poorly co-ordinated reserves, it collapsed under the pressure of the Waffen-SS and the Luftwaffe; where it had modern concrete and a narrow front, it held out until the capitulation.

The Grebbe Line and Fortress Holland

The Dutch defence plan assumed that the army would not defend the whole country. Its core was to shield the western provinces – North Holland, South Holland and Utrecht – known as Fortress Holland (Vesting Holland), until Allied help arrived. In the east and south of the country the lines on the IJssel and the Maas were merely to delay the enemy. Access to the Fortress from the north was barred by the Afsluitdijk, and from the east by the old New Dutch Waterline, a system of fortifications and land prepared for flooding. At the beginning of 1940, however, the new Commander-in-Chief, General Henri Winkelman, concluded that a defence on the Waterline would surrender Utrecht to the enemy and expose Amsterdam, and he adopted as the main defensive position the Grebbe Line further east, running from Lake IJssel to the Rhine at the foot of the Utrechtse Heuvelrug hills.

The line dated from the eighteenth century and had been renovated only in the last years before the war. The shelters built there were designed on the principles of 1914–1918 and were poorly protected on the flanks and from the rear, and the government, unwilling to antagonise local people, refused to allow trees to be felled and buildings demolished in the field of fire. The weakest point was the Grebbeberg itself: the ground in front of the hill could not be flooded because the pumping station had not been completed, and the zoo on its summit was still admitting visitors in May – including German officers in civilian clothes, who studied the positions from its observation tower. The defence in depth consisted of an outpost line, a front line on the eastern slope, a stop line (stoplijn) on the ridge and a rear line along the Rhenen–Veenendaal railway embankment.

The sector was defended mainly by Lieutenant Colonel W. F. Henninck’s 8th Infantry Regiment of the 4th Division, part of Major General Jacob Harberts’s II Corps. Opposite stood Generalleutnant Carl von Tiedemann’s German 207th Infantry Division from Georg von Küchler’s 18th Army, reinforced by the SS regiment Der Führer from the SS-Verfügungstruppe, the armed SS units from which the Waffen-SS soon grew. The division was a reserve formation without combat experience; the SS men were well trained and heavily armed with automatic weapons, but they too had yet to see action. The German forces totalled some 23,000 men.

Three days on the Grebbeberg

German troops crossed the border at dawn on 10 May, when Germany attacked in the West. Resistance on the IJssel delayed them so that they reached the Grebbeberg only in the evening. On 11 May the Der Führer regiment attacked the outpost line. German artillery fire cut the telephone lines, and the garrisons of individual positions, which did not support one another with fire, were eliminated one after another. At around 6 p.m. the last outpost surrendered. A night counter-attack, ordered by General Harberts in the belief that there were only a handful of Germans in the outposts, collapsed before it reached the enemy, because Dutch troops on the ridge, who had not been warned, opened fire on their own battalion. That same evening a field court martial sentenced to death and shot an artillery sergeant, Chris Meijer, accused of abandoning his post. After the war this sentence, passed under pressure from Harberts, who wanted to set a “deterrent example”, became one of the most controversial episodes of May 1940.

On 12 May, after an artillery bombardment lasting many hours, which did not destroy the fortifications but sapped the morale of the conscripts, the SS men captured the eighteenth-century Hoornwerk redoubt and forced their way onto the slope. One Dutch counter-attack after another failed, and in one of them the commander of the II Battalion of the 8th Regiment, Major Johan Jacometti, was killed. In the evening the commander of the III Battalion of Der Führer, Hilmar Wäckerle – in 1933 the first commandant of the Dachau concentration camp – broke through the stop line against orders with two companies and got as far as the railway embankment at Rhenen. There his unit was stopped by military police (Koninklijke Marechaussee) under Captain G. J. W. Gelderman and surrounded in factory buildings. The commander of the field army, General Jan van Voorst tot Voorst, sent all available reserves to the Grebbeberg, including Brigade B, and ordered a counter-attack from the north, from the village of Achterberg, for 13 May.

On 13 May the counter-attack got under way late, at around 8 a.m. The battalions of Brigade B, made up of middle-aged reservists exhausted by a day-long march, collided with an attack by two SS battalions which at the same time were meant to roll up the line from the north. At around noon the Dutch infantry began to fall back. The Dutch asked for RAF support, but the British aircraft were fighting in Belgium and France, so the last serviceable Dutch bombers and fighters were sent over the Grebbeberg. On the hill itself the 207th Division went into action for the first time and, after two waves of attack, took the stop line. The commander of the I Battalion of the 8th Regiment, Major Willem Pieter Landzaat, defended his command post to the end and was killed; after the war he was posthumously awarded the Military William Order. The encircled Wäckerle tried to break out, according to Dutch accounts using prisoners as human shields and dressing SS men in Dutch uniforms, in open violation of the laws of war; both attempts were beaten off.

An air attack proved decisive. At around 1.30 p.m. twenty-seven Junkers Ju 87 dive-bombers attacked the Grebbeberg. The physical damage was slight, but the howl of the Stukas’ sirens broke what was left of morale: the retreating Brigade B turned to flight, followed by the reserves at the embankment in Rhenen. At around 4 p.m. Captain Gelderman, who that morning had ordered food for six hundred men, had fifteen with him. By evening an eight-kilometre gap had opened up. At 8.30 p.m. General van Voorst tot Voorst ordered three corps to abandon the Grebbe Line and the position on the Waal and Linge and to withdraw during the night to the eastern front of Fortress Holland. The withdrawal, covered by morning mist, succeeded. The Germans became aware of it only on the morning of 14 May.

According to the figures of the Netherlands Institute of Military History (NIMH), 18 officers and 344 NCOs and men were killed in the fighting for the Grebbeberg, and 20 went missing; other tallies speak of more than 400 dead. Official German losses amounted to about 240 killed, and historians’ estimates usually fall in the range of 250–300. Most of the Dutch soldiers lie in the military cemetery on the Grebbeberg.

The Afsluitdijk and Kornwerderzand

In the north of the country the situation was entirely different. The three northern provinces had deliberately been left almost undefended, and the road from Friesland to North Holland was barred only by the Afsluitdijk – a 32-kilometre dam completed in 1932, which had cut off the former Zuiderzee inlet from the sea and turned it into the IJsselmeer lake. At its eastern end, by the Kornwerderzand locks, modern fortifications had been built in the last years before the war: a dozen or so casemates and shelters of thick reinforced concrete, with heavy machine guns and anti-tank guns. The garrison of about 225 men was commanded by Captain Christiaan Boers. The whole northern sector was under the command of the navy, from its base at Den Helder.

The dam offered an attacker no cover whatsoever. Generalmajor Kurt Feldt’s German 1st Cavalry Division occupied Friesland in two days and on the afternoon of 12 May, having broken through the forward positions, came up before Kornwerderzand. In the evening the first patrol, sent to check whether the fortifications were manned, came under machine-gun fire; two Germans were killed. Feldt had no heavy siege artillery, because the train carrying his mortars was held up at a demolished bridge. On 13 May the Luftwaffe bombed the fortifications several times, but the anti-aircraft defences, reinforced during the night, forced the aircraft to be more cautious, and the bombs did not penetrate the concrete. Late in the afternoon, after an artillery bombardment, several sections on bicycles set off along the crest of the dam. Boers let them come to within a few hundred metres and then opened fire. Pinned down on the open dam, the Germans withdrew only under cover of darkness. Dutch official historiography regards this action as a reconnaissance in force rather than a real assault; some authors speak of an attack by a battalion.

On the morning of 14 May the Germans shelled Kornwerderzand again, but this time the gunboat Johan Maurits van Nassau replied from the Wadden Sea, directed by observers in the fortifications and by the command at Den Helder. Its 150 mm guns forced the German batteries to change position. Feldt gave up further attempts on the dam and began gathering barges to cross the IJsselmeer to the coast of North Holland. The crossing took place only after the capitulation. The gunboat, sailing for England that same day, was sunk by German bombers.

Losses were negligible, contrary to a legend that arose as early as May among local people, who told of lorries full of German corpses. According to German reports, five soldiers were killed and about 25 wounded in the fighting for Kornwerderzand. On the Dutch side, an earlier fighter attack on the forward posts had killed one soldier and two civilians. Kornwerderzand remained in Dutch hands until the capitulation of 15 May; Boers told his men that they had fought “like lions”, but that the army had lost elsewhere.

A hope extinguished

On the first day of the war it seemed that the Grebbe Line and the Afsluitdijk would buy the Dutch time: in the north and east the Germans were stuck, and around The Hague the paratroopers had suffered a defeat. But by 13 May the German 9th Panzer Division had already crossed the bridges at Moerdijk and Dordrecht, seized by paratroopers, and stood on the south bank of the Maas in Rotterdam. The Allies could not come to the rescue: the French 7th Army was falling back towards Antwerp, and on the Meuse at Sedan the German breakthrough that would decide the fate of the whole campaign was beginning. On the morning of 13 May Winkelman judged the situation critical. At noon Queen Wilhelmina, and in the evening the government, sailed for Britain, and full authority in the country passed to the Commander-in-Chief. The loss of the Grebbeberg that same day deprived the army of its last strong position in the east.

Significance

The Battle of the Grebbeberg was the bloodiest land battle of the Dutch campaign and its turning point on the eastern front. It did not, however, bring about the capitulation: the field army withdrew in good order to the Waterline, which the Germans never attacked. The capitulation was forced a day later by the bombs falling on Rotterdam and the threat of Utrecht’s destruction. What the Grebbeberg did show was how little an untried conscript army with obsolete weapons, without radio communications or air cover, could achieve against an opponent able to combine artillery, infantry and air power. The psychological effect of dive-bomber attacks, seen the same day at Sedan, became one of the symbols of Blitzkrieg.

Kornwerderzand passed into Dutch memory as one of the few positions on the Western Front in 1940 that could not be taken. After the capitulation Captain Boers joined the underground organisation Ordedienst; arrested by the Germans, he was shot in May 1942 at Sachsenhausen concentration camp. Hilmar Wäckerle was killed in 1941 on the Eastern Front. After the war a military field of honour was established on the Grebbeberg, where soldiers who fell elsewhere in the Netherlands also lie, and the casemates of Kornwerderzand now house a museum.