The 'Battle of the Grebbeberg' was fought between German and Dutch forces as a major engagement during the 'Netherlands Campaign' resulting from the German 'Gelb' invasion (11/13 May 1940).

In the 1930s, the Dutch government had pursued a policy of strict neutrality. After the end of World War I in 1918, the Dutch parliament had supported a disarmament policy because it was popularly believed that World War I had been 'the war to end all wars'. However, when the threat of the revival of German aggressive policies under the impetus of the Nazi party became more apparent, the Dutch government decided to reinforce and retrain its armed forces. During the 1930s, therefore, the Netherlands' general defensive strategy was seen in the light of a possible attack by Germany, one of the Netherlands' neighbours. In that eventuality, the Dutch army was to fall back on the 'Hollandsche Waterlinie' (Dutch waterline), a series of water-based defences conceived by Prince Maurice of Nassau early in the 17^th century. This formed part of 'Vesting Holland' (fortress Holland), the Dutch national redoubt. It was expected that assistance for the Dutch would then arrive from France and the UK. To defend the redoubt, it was necessary to slow the German advance in order to give as much of the Dutch forces as possible the chance of assembling in the 'Vesting Holland'.

To this effect, several defensive lines were built throughout the country. The 'Maaslinie' and the 'IJssellinie' were constructed along the Maas and IJssel rivers, and were designed to detect German incursions into Dutch territory and to delay the Germans in the first hours of an invasion. The fortress at Kornwerderzand on the narrow Afsluitdijk guarded the northern approach to the 'Vesting Holland', while the Peel-Raamstelling (Peel-Raam position) in North Brabant guarded the southern approach. Any attempt to approach the 'Vesting Holland' through the central part of the country would be delayed in the 'Grebbelinie' (Grebbe line).

Early in 1940, the Dutch commander-in-chief, Generaal Henri Gerard Winkelman, redesignated the 'Grebbelinie' as the Main Defence Line, because defending the east front of the 'Vesting Holland' would bring the major city of Utrecht into the front line and the Germans too close to Amsterdam, the Dutch capital.

The 'Grebbelinie' had been built in 1745 and had been used for the first time in 1794 against the French. It was maintained throughout the 19^th century, but had been neglected since the start of the 20^th century as it was thought to have become obsolete, and in 1926 most of its fortifications were discarded. When Germany became a potential threat, however, the Dutch government decided to recommission the 'Grebbelinie'. In the later 1930s, therefore, a series of pillboxes and casemates were constructed in the area to the south of the IJsselmeer and north of the Rhine river. The 'Grebbelinie' was constructed according to French military principles which had proved successful in World War I but had then, unknown at the time of construction, become obsolete. There were major flaws in the design of the pillboxes, which were difficult to defend against attack from the flanks and rear. The fixed weapons were antiquated, many of them dating back to World War I. Because the Dutch government did not want to antagonise local residents, permission to remove buildings and trees in the line of fire was refused, which greatly reduced the effectiveness of the defences and gave attackers plenty of cover. The trench system was also based on World War I principles, and comprised a Voorpostenlijn (outpost line), a Frontlijn (front line) and a Stoplijn (final line).

The position at the Grebbeberg suffered from a lack of serious security measures. The government did not want to interrupt tourism as the local economy of Rhenen was dependent on revenues from the Ouwehands Dierenpark, a zoo located on a hill near Rhenen, the Grebbeberg. In the months leading up to the invasion, German officers in civilian clothes visited the zoo and used its look-out tower to survey the local defences. The government estimated that the 'Grebbelinie' (later 'Grebbelijn') would be completed in November 1940, and in May 1940 the bomb-proof pumping station at the Grebbeberg, which was necessary for the control of local flooding, had not been completed. Because of its lack of controllable inundation, the German intelligence-gatherers realised that the Grebbeberg would be a vulnerable spot in the 'Grebbelijn'.

The Grebbeberg was defended by the 8^th Infantry Regiment under the command of Luitenant-kolonel Hennink, and was supported by one battalion of the 19 Infantry Regiment. The defending units were part of the 4^th Division under the command of Kolonel van Loon. The 4^th Division and 2^nd Division constituted the II Corps under the command of Generaal-majoor Jakob Harberts. On the Grebbeberg itself were three batteries of the 8^th Artillery Regiment and three of the new 19^th Artillery Regiment. The batteries of the 8^th Artillery Regiment were 1-I-8 RA and 2-I-8 RA armed with the 75-mm (2.95-in) 7 veld (Krupp Model 1903), and 2-III-8 RA with the 149.1-mm (5.87-in) L/17 (sFH 13) howitzer. Those of the 19^th Artillery Regiment were the three batteries of II-19 RA armed with the antique 120-mm (4.72-in) Lang staal.

The German forces were Generalleutnant Karl von Tiedemann’s 207^th Division of some 17,500 men and the SS-Standarte 'Der Führer' of about 6,000 men. The 207^th Division was a reserve formation and possessed only minimal combat experience, and while the SS regiment, of brigade size, was certainly elite, its men had no combat experience. These units were supported by about 50 pieces of artillery.

At 03.55 on 10 May 1940, Generaloberst Fedor von Bock’s Heeresgruppe 'B' crossed the border into the Netherlands. The 207^th Division was a formation of General Georg von Küchler’s 18^th Army, and had been tasked with overrunning the Grebbeberg within a day. Resistance at the 'IJssellign' near Westervoort was fiercer than anticipated and it was dusk by the time the Germans had occupied Wageningen, the city directly to the east of the Grebbeberg. The 207^th Division, reinforced by the SS-Standarte 'Der Führer', readied itself to assault the hill on the following morning.

To mount a direct assault on the Grebbeberg, the Germans had to breach the Voorpostenlijn, which covered an area 1.85 miles (3 km) wide directly in front of the Grebbeberg, which had not been flooded. The line was manned by two companies of the 3/8^th Infantry Regiment. In the early hours of 11 May, German artillery opened fire on the line of outposts, disabling the Dutch defenders' telephone system and making it impossible for them to call for artillery support. At dawn, the SS brigade launched a direct assault on the outposts, which were of a largely improvised nature and comprised sandbags and wooden obstacles. The Dutch defensive fields of fire did not overlap, so the German forces were able to neutralise them individually by sending two teams of machine gunners to attack a single position: one team provided covering fire while the other exploited the blind spots to launch a flanking attack.

In the northern part of the line, on the edge of the inundated area, the Germans ran into a section of the 19^th Infantry Regiment which, because it was part of a different unit, had difficulty in the co-ordination of its actions with the other Dutch positions. This section broke after a short skirmish and retreated to the west, thereby creating an open flank which the Germans exploited by encircling the more southern Dutch sections. Near the Rhine river the Germans used a dike to approach defending forces from the rear without interference. Dutch supporting fire from the Frontlijn was largely ineffective because the area between it and the Voorpostenlijn was occupied by orchards, which kept the Germans out of sight. Now that the SS forces had succeeded in approaching the Dutch forces from the rear, the Voorpostenlijn could be neutralised: at 18.00, the last Dutch section surrendered and the Voorpostenlijn fell into German hands.

During the evening, German armoured cars tried to attack the hill itself but were repelled by a 47-mm anti-tank gun. At this time an artillery sergeant, who had been arrested for abandoning his post, was court-martialled and executed by firing squad. After the war, this court martial was to become controversial because of the possibility that undue influence had been exercised by Harberts, commander of the II Corps. This incident, together with unfounded rumours of a massive rout in the Voorpostenlijn, incited Harberts into setting an example for other Dutch forces. At 21.00, he ordered the 2/19^th Infantry Regiment to begin a counterattack under the cover of darkness against the outposts. Harberts estimated that there were about 100 Germans in the Voorpostenlijn, but in reality the 2/19^th Infantry Regiment faced some 3,000 SS troops. At the Stoplinj, which was situated directly on the Grebbeberg, the 2/19^th Infantry Regiment came under fire from other Dutch troops, who had not been informed of the impending counterattack. The confusion that followed caused the attack to lose momentum even before it had made contact with the Germans, and by the time order had been restored dawn had broken and the counterattack was called off. One positive side-effect of the counterattack had been that Dutch artillery support forced the Germans to abandon their own planned night attack.

After the seizure of the Voorpostenlijn during the previous day, the focus of the German force was on 12 May was the seizure of the Frontlinj, which ran along the eastern slope of the Grebbeberg. von Tiedemann decided to initiate a major assault on the hill, which was defended by four companies of the 1 and 2/8^th Infantry Regiment reinforced by one machine gun company and one anti-tank unit in the nearby casemates. There was a much larger number of Dutch machine guns in the Frontlinj, so this time there were no blind spots in which German units could hide. von Tiedemann realised that an all-out assault like that of the previous day would not work, and therefore ordered an artillery barrage which lasted for the better part of the morning. The artillery bombardment did not destroy the defensive works, but did undermine the morale of the Dutch units, which were composed mainly of conscripts.

At 12.40, the German artillery bombardment came to an end and the SS brigade attacked the Hoornwerk, an 18^th-century fortification which had to be seized early in the engagement. The defenders' ammunition supply was low as a result of skirmishes during the preceding night, and early in the afternoon the Dutch started to give way. After a short engagement, the Hoornwerk fell and the Germans stormed the hill. The Germans threatened to outflank the Dutch casemates, which could lay their fore only on the area directly in front of them. A fierce battle ensued on the wooded slope, but their automatic weapons gave the SS soldiers an advantage. The Dutch did not have sufficient forces in reserve to initiate a counterattack.

At 16.00, the Dutch troops at the Stoplinj on top of the Grebbeberg encountered the first German units. A frantic attempt was made to drive the Germans back to the Frontlinj, but the Dutch counterattack was no match for German firepower. To the north of the road connecting Rhenen and Wageningen, Majoor Johan Henri Azon Jacometti, commander of the 2/8^th Infantry Regiment, personally led a counterattack, but this failed after Jacometti had been killed. Reinforcements were necessary if the Dutch were to halt the German advance, reinforcements were necessary, and the 2/19^th Infantry Regiment, the unit which had executed the aborted counterattack during the previous night, was ordered to advance to the Frontlinj. The battalion suffered the same fate as it had the night before when nervous Dutch troops once again opened fire on the battalion. The demoralised soldiers withdrew to safety and the attack petered out.

As a result of its concentration, the SS brigade was now vulnerable to Dutch artillery fire. As the German advance was dependent largely on the strength of the SS brigade, the destruction of a large part of this unit could turn the tide of the battle. However, in order to avoid hitting their own troops, the Dutch artillery executed a mainly pre-arranged fire plan aimed at the interdiction of German reinforcements. Firing on the German concentration was limited to some individual commanders using their own initiative. There was also some effective fire from mortars.

Late in the afternoon and early in the evening, the SS brigade cleared the area between the Stoplinj and the Frontlinj of all resistance. Even so, by 20.00 the penetrated area was still quite limited with a depth of 765 yards (700 m) and a width of 1,095 yards (1000 m). There was no great higher-level pressure on von Tiedemann to make haste as the main German attack was near Rotterdam. The commander of the third battalion of the SS brigade, SS-Obersturmbannführer Hilmar Wäckerle, was not satisfied with the limited progress which had been achieved, however, and considered the fact that the 'Grebbelinj' had not yet been breached to be a stain on his personal honour. Furthermore, he noticed that the Stoplinj had lost most of its cohesion because of the exhausting counterattacks. Completely in line with his impetuous character and the fearsome reputation he wished to create for the Waffen-SS, Wäckerle ignored his orders and moved two companies of his battalion forward into the Stopline. An improvised attempt was made to penetrate the Stoplinj in two places: the first attempt was made by Wäckerle himself near the road linking Rhenen and Wageningen and the second farther to the south near the Rhine river. The first attempt succeeded, and Wäckerle’s men infiltrated the Stoplinj and immediately advanced unopposed for 1,640 yards (1500 m) with one company, driving the disheartened Dutch defenders before them. The SS soldiers then stumbled on the Ruglijn (final line), which was formed by the railway line linking Rhenen and Veenendaal. The disadvantage of the rapid SS advance now became apparent: as no other German units had participated in the advance, the latter was not exploited and most of the Stoplinj held firm, leaving Wäckerle surrounded deep in Dutch territory. His only hope for a further breakthrough now rested on a spontaneous collapse of the Dutch defences.

At the same time, the Dutch situation seemed to improve as reinforcements arrived. The 2/19^th Infantry Regiment had reassemble along the Ruglijn and the 1/46^th Infantry Regiment had been despatched from the Betuwe to assist in the defence of the 'Grebbelinj'. The 3^rd and 4^th Hussar Regiments also arrived on the scene from the north. The only way into Rhenen was the viaduct underneath the railway, which was defended by units of the Royal Marechaussee led by Kapitein G. J. W. Gelderman. The Royal Marechaussee was tasked with preventing any units from getting past the railway, be they Germans or retreating Dutch forces. Gelderman was in the process of convincing withdrawing Dutch forces to resume fighting when Wäckerle’s SS company reached his position. Gelderman gave the order to open fire and many Dutch and German soldiers were hit. The SS company was successfully contained in a factory located between the railway and the Rhine river.

The reinforcements were sent in by the commander of the Field Army, General­løjtnant Jan Joseph Godfried Baron van Voorst tot Voorst, to stabilise the front. van Voorst also decided to take additional measures. The number of troops at his disposal was very limited because most reserve forces were involved in repelling an airborne attack near The Hague. He could deploy seven battalions: the 2/11^th Infantry Regiment, the 1/20^th Infantry Regiment and five battalions of the newly arrived Brigade B. The safest option was to yield the Stoplinj and regroup at a new defensive line, but the Dutch army lacked the engineer capacity to create such a line quickly, and thus van Voorst ordered the forces in the Stoplinj to recapture the Frontlinj. An officer from the general staff sent to the 4^th Division, Kapitein A. H. J. L. Fiévez, drew up an attack plan on the night of 12 May. According to this, three of the seven available battalions were to reinforce the troops at Grebbeberg, the Stoplinj and the Ruglinj, while the other four were to execute a flanking attack from the village of Achterberg to the north of the Grebbeberg. The purpose of this flanking attack was not just to drive the German forces from the hill, but also to stabilise the local situation. In the late evening, the situation to the north of the Grebbeberg had worsened considerably, and the counterattack also served the purpose of reversing the situation there. As night fell, a single Dutch section still occupied the Frontlinj, and this surrendered only after the Dutch army capitulated.

By the morning of 13 May, von Tiedemann had lost all contact with Wäckerle and was wholly confused by the situation on the Grebbeberg. He assumed that Dutch reinforcements were being assembled on the hill but noticed that the strength of the defences to the north of the Grebbeberg had deteriorated, and decided to open a second axis of attack in this sector. For the first time, the 207^th Division was to be deployed, not against the endangered Dutch sector to the north of the Grebbeberg, but on the Grebbeberg itself, in order to pin down Dutch forces there and to cleanse the Stoplinj of defenders. The task of attacking the Dutch troops to the north of the hill was given to the two remaining battalions of the SS brigade, which had seen continuous action for the past two days. At the same time, the Dutch were preparing their own attack in the very same sector.

Each side’s attack was supported by indirect artillery fire. The Dutch requested air support from the British, but the Royal Air Force was unable to divert any warplanes from the ongoing 'Battle of France'. Instead, the Royal Netherlands air force despatched the last aircraft it could spare: four completely obsolete Fokker C.X single-engined biplane light bombers, which were protected by the last operational fighters. Some 30 bombs were dropped on the German artillery positions in front of the Grebbeberg, and the bombers and escorting fighters then strafed the German forces along the road linking Rhenen and Wageningen until they ran out of ammunition. The Dutch used artillery too, but its effectiveness was diminished by the now well-rooted fear of hitting their own forces. The Germans also used artillery when their attack started late in the morning.

The Dutch counterattack near Achterberg should have started at 04.30 but was delayed to 08.00. Brigade B, which had arrived the evening before, supplied the 1 and 3/29^th Infantry Regiment, the 2/24^th Infantry Regiment and the 1/20 Infantry Regiment which, however, were ill-prepared and exhausted from having marched right through 12 May. It was often unclear to the troops what their exact objectives were, what the terrain in front of them looked like and what resistance they could expect. The battalions comprised middle-aged men, who had not been re-trained for service and had not been able to create strong bonds of comradeship. These factors contributed to less cohesion in the ranks, which would prove fatal in the battle to come.

At first, little opposition was encountered as the Dutch advanced to the Stoplinj and reoccupied the positions which had been abandoned so hastily during the previous evening. But the situation deteriorated after the advance had passed the Stoplinj as the Dutch advance walked into a German artillery bombardment which preceded the SS attack. While it would have been best for the Dutch to move into defensive mode and repel the attack, the Dutch divisional command was unaware of the German intentions and ordered that the advance was to continue. Many troops were killed by German artillery and by supportive fire from their own machine guns. The confused battalions, many of which had lost their non-commissioned officers, started to retreat to the Stoplinj at 12.00. A second wave of attackers faltered and also started to fall back, and in some places the Stoplinj was abandoned. The retreat was exacerbated at 14.00 as 27 Junkers Ju 87 single-engined dive-bombers attacked. Though the attack was not aimed at Brigade B, but rather at the positions on the Grebbeberg itself, it was enough to cause panic in the retreating battalions. A sauve qui peut mentality raised its head among the Dutch troops, and the defence mounted by the 4^th Division effectively collapsed as events on the Grebbeberg itself had taken a turn for the worse.

The success of the Dutch counterattack had also depended on whether or not the Stoplinj on the Grebbeberg itself would hold, for the elimination of the Stoplinj would remove any chance of a successful defence. To make sure the line would hold, it was necessary to commit fresh troops to reinforce the line. Communication was made difficult because of the presence of Wäckerle’s pocket of SS troops. On the preceding day, many trenches to the south of the road linking Rhenen and Wageningen had been abandoned by Dutch forces. Fièvez, who did not have a clear picture of the situation near the Stoplinj, had designated the Ruglijn near the railway in Rhenen as the main line of defence, and this caused the Stoplinj to be undermanned. Furthermore, as it served only as an assembly area for incoming reinforcements rather than as a true defensive perimeter, the Ruglinj could not be developed into a fully fledged defensive position. By the time these mistakes became apparent, it was too late to reinforce the endangered Stoplinj.

The fatal decision not to cut down the wooded areas near the Stoplinj now became detrimental to the defenders, who were unable to keep at bay the German forces exploiting the cover provided by the trees. The Stoplinj was intended as the last real line of defence serving as the point from which a German breakthrough could be countered; it was thus a position lacking any depth. Once the Stoplinj had been breached, the 'Grebbelinj' would be jeopardised. After a brief artillery barrage the Germans launched their first attack. Although it was generally unsuccessful, some German units managed to break through the line. Most of the German troops in this attack were older and less experienced, and had a tendency to panic. But the German commanders were aware of this possibility and after a second artillery bombardment another attempt was made by the second echelon. This attempt proved to be successful shortly after 12.00 and, using the earlier penetration, the Stoplinj was put largely out of action. A fierce struggle ensued in the woods as the German forces started their descent into Rhenen. Most Dutch command posts were located behind the Stoplinj and now came under attack. One command post was valiantly defended by the commander of the 1/8^th Infantry Regiment, Majoor Willem Pieter Landzaat, who ordered his men the order to 'stand firm behind the rubble' and to 'resist until the last bullet'. Once the defenders had run out of ammunition, Landzaat thanked and dismissed his men and continued to defend the command post. His body was found after the battle by his wife. The attacking Germans had become nervous, and it took quite a few hours before the area between the Stoplinj and the railway had been cleared of Dutch troops. At 17.00, the German forces started to re-form for an attack on the Ruglinj. But Dutch morale had broken to so great an extent that such an assault was no longer necessary.

There were many Dutch soldiers in and around Rhenen, but most were in scattered groups guarding the railway. There was little co-ordination and the different commands in the area overlapped so that all oversight was lost. Most troops were exhausted and nervous because of the continuous artillery bombardment. Overall command in the sector had devolved to Luitenant-kolonel the Jonkheer de Marees van Swinderen, commander of the 4^th Hussar Regiment. He had not been informed of the situation on the Grebbeberg and sent no reinforcements to the Stoplinj, instead sending some troops back to Elst, some 3.7 miles (6 km) to the west of Rhenen, as a mobile reserve. This caused the cohesion of the Dutch forces in Rhenen to decrease still further. As the day progressed, more troops would leave the battlefield and retreat to the west.

Wäckerle’s stranded SS company had meanwhile spent an uncomfortable night in the factory. The SS soldiers made two attempts to break through the Ruglinj, during which Wäckerle violated the laws of war. The first attempt involved the use of Dutch prisoners of war as a human shield, and the second attempt involved the SS men’s advance in Dutch uniforms. The Royal Marechausse unit under Kapitein Gelderman, which had orders to shoot all men moving to the west, repelled both attempts. Wäckerle’s manoeuvring had failed, and the Dutch forces destroyed the viaduct. Wäckerle himself was badly wounded, and when his company was releived by German forces in the afternoon he went to Wageningen for treatment.

The same air attack that had caused Brigade B to the north of the Grebbeberg to turn tail and run, also hit parts of the Ruglinj and had the same effect: little physical damage was inflicted, but Dutch morale collapsed completely and the majority of the Dutch troops started to leave the battlefield at this point. At 16.00, Gelderman noticed with amazement that there were only 15 men left in his vicinity while he had ordered food for 600 earlier that morning. By this time, the entire 4^th Division had come to the conclusion that it had suffered a defeat and that only a retreat could save their formation. The reserves behind the line were caught in the withdrawal after rumours had spread that an official retreat had been ordered. One exception to this massive rout was a company of the 11^th Border Battalion, the last Dutch reinforcement sent to the Grebbeberg. In the evening, it crossed the final line and evicted German forces from the railway station, but ultimately its deployment did not make any difference and the battalion withdrew as Rhenen was being destroyed by fire.

The fall of the Grebbeberg was a huge blow to the Dutch. Defeat at this location meant the collapse of the entire 'Grebbelinj' and forced the Dutch to a full retreat of six divisions to the eastern front of the 'Waterlinj'. This retreat was quickly and successfully executed during the afternoon and late evening of 13 May and finalised during the morning of 14 May, the German forces being unaware the Dutch lines had been abandoned until that morning.

The Dutch casualties were heavy. In total, 18 officers and 399 other ranks had been killed during the three days of battle. The German casualties were lower, but this has led to some dispute as many eye-witness reports do not match the figures that the Germans released: the official number is 238 men killed, but estimates suggest that the real figure was between 250 and 300 men killed.

The eastern front of 'Vesting Holland' would not be attacked as during the evening of 14 May the Dutch, after the 'terror bombing' of Rotterdam, surrendered in all provinces except Zeeland, where they continued to resist.