The 'Battle of Rotterdam' was fought between German and Dutch forces for the city of Rotterdam in the course of the German 'Gelb' invasion, and ended with the German 'terror bombing' of the city (10/14 May 1940).

Rotterdam had no prepared defences, and had not been included in any Dutch strategic defence plan. The city lay relatively far from the boundaries of the 'Vesting Holland' and some distance from the coast, and the troops stationed there were primarily of training establishments and some miscellaneous smaller units. A modern artillery battalion with 12 105-mm (4.13-in) guns was located in Hillegersberg, and these guns had a range of more than 17,500 yards (16000 m), which was sufficient for the engagement of targets almost anywhere around Rotterdam. The garrison commander was a military engineer, Kolonel P. W. Scharroo, who led a garrison comprising some 7,000 men, of whom only 1,000 from the Dutch marines and 39^th Infantry Regiment had any combat role. Around the Nieuwe Maas river, seven platoons of light anti-aircraft artillery were deployed, these being equipped with heavy machine guns as well as 20-mm Oerlikon cannon and 20-mm Scotti cannon. One heavy anti-aircraft battery was stationed to the north of the Nieuwe Maas river, and there were two other batteries and four anti-aircraft platoons in the Waalhaven area. The Waalhaven air base was also the home of the 3^rd 'Java' Squadron of the Royal Netherlands air force equipped with Fokker G.I twin-engined heavy fighters. Some 11 operational examples of this fighter, fully armed and fuelled, were stationed at Waalhaven on 10 May, and during the German bombing of the airfield, nine of these managed to take off and attack the German aircraft, of which 14 became confirmed 'kills'.

The original German plan called for a task force from Waalhaven, which was to have been taken by an air-landed assault, to attack the city and seize the bridges over the Nieuwe Maas river exploiting the advantage resulting from surprise. When the plans were evaluated, it was decided that the chances of the task force achieving success were below the acceptable level, so the Germans devised a new plan: 12 specially adapted Heinkel He 59D twin-engined floatplanes were to land on the Nieuwe Maas river with two platoons of the 11^th Kompanie of the 16^th Luftlanderegiment of Generalleutnant Hans Graf von Sponeck’s air-landing 22^nd Division (Luftlande), four engineers and a three-man company troop. These 90 men would seize the bridges, and would be reinforced by a 36-man platoon of Luftwaffe airborne soldiers from the 1^st Fallschirmjägerregiment of Generalleutnant Kurt Student’s 7^th Fliegerdivision. These were scheduled to land at the Feyenoord football stadium, close to the Nieuwe Maas river. Subsequently, units from Waalhaven would be sent in with additional support weapons.

In the early morning hours of 10 May, the 12 He 59 floatplanes landed on the Nieuwe Maas river and their crews launched rubber dinghies each able to carry six soldiers and their equipment; about 80 German soldiers landed on both banks of the river and an island. The Germans quickly seized some of the bridges, which were not guarded, and the only resistance they met was from some Dutch policemen.

Oberstleutnant Dietrich von Choltitz, commander of the 3/16^th Luftlanderegiment, began to organise his men after they had been landed at the Waalhaven air base, and then despatched them to the bridges in Rotterdam. The Dutch had not stationed many soldiers in the southern part of the city: one unit comprised butchers, bakers and about 90 infantrymen, the last reinforced by infantrymen who had withdrawn from the airfield. The Dutch troops concealed themselves in houses on the route to the bridges, and there ambushed the approaching German troops. Both sides suffered casualties. The Germans managed to bring up an anti-tank gun, and the Dutch had to yield under the ever-increasing pressure. The German force then moved on to the bridges, quickly followed by the bulk of the 9^th Kompanie of the 16^th Luftlanderegiment.

Meanwhile, the staff of 3/16^th Luftlanderegiment had run into the Dutch in the square. von Choltitz’s adjutant took charge of an assault on the Dutch position but was mortally wounded in the process. When the Germans sought another route to the bridges to bypass the Dutch stronghold, they managed to find a salient which advanced troops had created along the quays. It was at about 09.00 that the bulk of the 3/16^th Luftlanderegiment made contact with the defenders of the bridges.

The Dutch company in the south of the city was able to stand its ground until well into the afternoon of 10 May. It was then assaulted by the newly landed 10^th Kompanie of the 16^th Luftlanderegiment, supported by mortars, and the Dutch troops surrendered when they ran out of ammunition.

The Dutch troops in the north of the city were alerted by the sound of aircraft close overhead. The garrison headquarters were temporarily manned only by a captain, who ordered the assembly of the available troops and co-ordinated the distribution of ammunition. Many small detachments were sent out to the bridges, the three nearby railway stations, and the areas around the Nieuwe Maas river where landings had been reported. The Germans noticed the activity on the Dutch side and the first contacts with the Dutch forced the Germans to consolidate their forces round the bridges.

The first Dutch countermeasures were executed by a small delegation of marines and an incomplete army engineer company. The Dutch took position round the small German pocket to the north of the bridges and started deploying machine guns at numerous tactically advantageous points. There soon followed the first serious exchanges of fire between the invaders and Dutch regular army units, and the Germans were gradually pushed back to the confines of the narrow perimeter around the traffic bridge. Both sides suffered considerable losses.

The Dutch steadily compressed the Germans in the bridgehead into a quickly shrinking pocket as many civilians watched. Halfway through the morning, the Dutch navy assigned two small navy vessels (the small and obsolete gunboat Z 5 and the motor torpedo boat TM 51) to assist the defenders at the bridges. The gunboat attacked the Germans at the traffic bridge on the northern side of the Noordereiland (an island in the river) on two occasions, the second time accompanied by the motor torpedo boat. About 75 75-mm (2.95-in) shells were fired at the invaders, but to little effect. During the second attempt, the Luftwaffe dropped a number of bombs on the naval vessels and caused substantial damage on the motor torpedo boat. Both ships retired after the bombing attack having suffered the loss of three men killed.

Meanwhile, the Germans had been reinforced with a number of 37-mm PaK 36 anti-tank guns and a few 75-mm (2.95-in) infantry guns. They manned the houses along the northern side of the island with heavy machine guns and placed a few 80-mm (3.15-in) mortars in the centre of the island. The continuing battle for the northern river bank caused the Germans to withdraw to the large National Life Insurance Company building, at the head of the traffic bridge. As a result of the poor firing arcs the Dutch had on the building, the Germans were able to hold the building without much difficulty. Dutch troops occupying nearby houses were forced to fall back by accurate and sustained mortar fire. That stalemate, which began during the afternoon of 10 May, would remain unchanged until the surrender of the Netherlands on 14 May.

Aware that his small garrison was dealing with a serious German attack, Scharroo had requested substantial reinforcements from The Hague. Many reinforcements would be sent, all coming from the reserves behind the 'Grebbelinie' or from the eastern front of 'Vesting Holland'. During the night and into the early morning of 10/11 May, Scharroo received reinforcements from the northern sector of 'Vesting Holland' and reorganised his defences. He deployed troops along the entire river and to the west, north and east of the city. The latter was done because Scharroo feared that the landed Germans would launch attacks on the city from these directions. His small staff was very much occupied with the numerous reports about phantom landings and treacherous civilian actions: these activities occupied the staff to the extent that no plans for organised countermeasures against the German bridgehead were drawn up for 11 May.

At 04.00, the fighting resumed around the bridgehead. The German spearhead was still formed by their 40- to 50-man force in the National Life Insurance building north of the traffic bridge. This building had become isolated from the rest of the German forces by Dutch progress on 10 May. All Dutch attempts to seize the building failed, but so did all German attempts to resupply or reinforce the isolated group. Germans trying to reach the building by crossing the bridge by motorcycle or car were either shot or forced back. The bridge had become a no-go area, dominated by machine guns from both sides.

The Royal Netherlands air force assisted the ground forces at Scharroo’s request. Dutch bombers began to attack the bridges, and although all of their bombs missed, a number of stray bombs hit German positions near the bridge, destroying a number of machine gun positions. Another raid followed, but the Luftwaffe responded with patrols by 12 Messerschmitt Bf 110 twin-engined heavy fighters, and when the Dutch bombers attacked the bridges but were immediately tackled by the German fighters. The Germans lost five aircraft and the Dutch three, but to the small Dutch air force this was a heavy price.

The Germans used the Holland America Line ship Statendam on which to site some of their machine guns. These positions attracted Dutch attention, and mortar and machine gun fire was soon directed at the German positions on the ship and adjacent installations. Many fires broke out and the ship itself caught fire, so the Germans quickly evacuated the vessel, which continued to burn until well after the capitulation on 14 May.

On 12 May, fighting resumed where it had ended on the previous day. Although the Dutch did not regain control of the city, the Germans were suffering heavily in the continuous assaults on their positions. Casualties mounted on both sides and the German command grew increasingly worried over the status of their 500 men in the heart of Rotterdam. von Choltitz was authorised by Student to withdraw his men from the northern pocket should he consider the operational situation required it.

To the north-west of Rotterdam, at the village of Overschie, forces which had been involved in the air landings at Ockenburg and Ypenburg assembled. von Sponeck had moved the remainder of his force from Ockenburg to Overschie, moving between Dutch forces in the area. In the village of Wateringen, the Germans encountered the guard squad of a Dutch command post and when two armoured cars appeared to support the Dutch defenders, the Germans fell back and then detoured. The majority of von Sponeck’s group succeeded in reaching the village Overschie, where they joined up with German survivors of the Ypenburg battle.

During the evening of 12 May, Scharroo received orders from general headquarters to put his whole effort into clearing the German resistance at the northern approaches to the bridges, and eventually to destroy the bridges. That order was a direct consequence of the arrival of Generalleutnant Alfred Ritter von Hubicki’s 9^th Panzerdivision at the Moerdijk bridges, which threatened the Dutch defence of 'Vesting Holland'. The commander of the local marines, Kolonel von Frijtag Drabbe, was ordered to destroy every German pocket of resistance in the northern end and occupy the northern bridge approach in order to secure the area and prepare the bridge for destruction. He formed a company (slightly more than 100 men) of his most experienced marines. Another company of navy auxiliary troops (also with a strength of about 100 men) was provided as back-up. These two companies were supported by two batteries of 105-mm (4.13-in) howitzers and two armoured cars, and a company of six 81-mm (3.19-in) mortars was also attached to the task force. The marines' advance was soon suppressed by fierce German machine gun fire from the south. The Dutch artillery had not fired a single round up to this point, but after a brief discussion with the artillery battalion commander, several salvoes were fired. All the Dutch shells fell short or over, however, and after corrections had failed to effect any improvement in accuracy, the artillery ceased fire. Meanwhile, the two M39 Pantserwagen armoured cars had arrived and attempted to approach the bridge. The Germans responded with fierce anti-tank fire, crippling one of the cars. Although the damaged car was able to retreat, it could no longer contribute to the assault. The second car remained at a safe distance and was not able to challenge the Germans in the National Life Insurance building. Since the commander of the mortar company convinced the colonel that his mortars would not be able to lay effective fire on the high building, the assault on the eastern side of the bridgehead was cancelled.

From the north-west, a platoon of Dutch marines advanced along the Nieuwe Maas river and reached the northern headland without any German challenge. However, the platoon was unaware of the occupation of the insurance building by the Germans and as it started to cross the bridge it was immediately spotted and the Germans opened fire from both sides. Many marines were hit, mostly fatally. Even so, the marines immediately returned fire with their carbines and light machine guns. After a few more marines had fallen, the remainder retreated, losing more of their number as they fell back. Others found shelter beneath the bridge, but were unable to leave again. The rest of the marines found shelter under the northern end of the bridge, and were soon engaged in a firefight with a small group of Germans also taking shelter there. The Germans in the insurance building launched suppressive fire at the group, and the Dutch retreated, leaving behind some casualties. After the war, the German occupants of the insurance building admitted that they had been on the verge of surrender. They were very short of ammunition, half of them had been wounded, and they had reached the point of utter exhaustion. But just when they were about to yield, the marines disappeared.

It was clear to the Dutch senior officers in Rotterdam that with the failed action against the bridges, all hope would have to be fixed on a successful defence of the northern river bank. In order to achieve a solid defence, seven companies of infantry were ordered to form a screen along the river. Each of the two bridges was covered by three anti-tank guns, and the three batteries 105-mm (4.13-in) howitzers at the Kralingse Plas were ordered to prepare barrages on both headlands.

Meanwhile, the first German tanks had arrived in the southern outskirts of Rotterdam. General Rudolf Schmidt, commander of the XXXIX Corps (mot.), was very reluctant to launch an all-out armoured assault across the bridges to the northern side, for he had received reports of firm Dutch opposition and the presence of Dutch artillery and anti-tank guns. The losses of tanks at the Island of Dordrecht and during an attempted bridge crossing at Barendrecht, where all four tanks had been destroyed by one anti-tank gun, had impressed the Germans to such an extent that they were convinced that only a tactical air bombardment of the direct vicinity of the northern headland could break the Dutch resistance.

It was around this time that the German high command became involved. Generalfeldmarschall Hermann Göring, commander-in-chief of the Luftwaffe, wished to launch an all-out aerial bombardment of Rotterdam city centre. However, both Schmidt and Student were opposed to the idea and believed that all that was needed was a tactical bombardment. General Georg von Küchler, commander-in-chief of the 18^th Army and responsible for operations in the Netherlands, instructed Schmidt that on the morning of 14 May that the Dutch commander was to be given an ultimatum in which unconditional surrender of the city would be demanded.

On the morning of 14 May, Schmidt prepared a quick note in the form of an ultimatum, in Dutch, to be handed to the Dutch commander of Rotterdam. Three German negotiators carried the ultimatum to the Maas river bridges. Despite being identified as truce negotiators, the three officers were nonetheless treated harshly by the Dutch. They were stripped of all their weapons, which were thrown into the water, then blindfolded and taken to Scharroo’s command post in the city. Scharroo was handed the note, which said that if resistance did not cease the Germans would destroy Rotterdam. Scharroo called general headquarters, and soon after this received a call with instructions from Generaal Henri Gerard Winkelman, commander-in-chief of the Dutch forces. The ultimatum had to be returned to the German commander with the reply that only a signed ultimatum, together with a statement of the name and rank of the commanding officer, would be accepted by the Dutch as a legitimate letter of ultimatum.

Scharroo sent his adjutant, Kapitein J. D. Backer, to the Germans with the Dutch reply. Meanwhile, Göring had ordered Oberst Walter Lachner’s Kampfgeshwader 54 'Totenkopf' to launch its 90 Heinkel He 111 twin-engined medium bombers from three bases near Bremen. Lackner led two-thirds of his force on to a course that would bring them onto the target from the north-east. The other 27 bombers were led by Oberstleutnant Friedrich Höhne and were to approach Rotterdam from the south. The estimated time of arrival over the target was 13.20.

The Germans accepted the reply from Scharroo, and Schmidt had his interpreter quickly draw up a new letter, more extended than the first, giving the Dutch until 16.20 to comply. He signed the new ultimatum with his name and rank. When Backer was being escorted by von Choltitz to the Maas river bridges, German bombers appeared from the south. Joined by von Hubicki and Student, Schmidt saw the aircraft and expostulated that 'My God, this is going to be a catastrophe!'

On the Noordereiland, panic struck German soldiers, most of whom were totally unaware of the events being played out between the senior commanders of each side and now feared that they were about to be attacked by their own bombers. von Choltitz ordered red flares to be fired, and when the first three bombers overhead dropped their bombs the red flares were obscured by smoke. The next 24 bombers of the southern formation closed their bomb-bay doors and turned to the west.

The other and somewhat larger formation of bombers now arrived from the north-east. This formation comprised 60 bombers which, as a result of the dense smoke, had been ordered to change their flight plan and, as a result, their approach angle with the Noordereiland in the south decreased dramatically. There was not a chance that the red flares, if actually seen, would be spotted in time before the bombs were dropped. Indeed, the entire formation unloaded its payloads over the Rotterdam city centre and a mix of 551-lb (250-kg) and 110-lb (50-kg) bombs rained down over the defenceless city.

In total, 1,150 110-lb (50-kg) and 158 551-lb (250-kg) bombs were dropped on the city, mainly in the residential areas of Kralingen and the mediaeval city centre. Most of them struck buildings, which immediately went up in flames. The fires across the city centre spread uncontrollably and, in the subsequent days, were aggravated as the wind grew stronger; they merged to become a firestorm. Reports later stated that 900 people had been killed, and 642 acres (2.6 km²) of the city centre had been destroyed. Some 24,978 homes, 24 churches, 2,320 shops, 775 warehouses and 62 schools were lost.

The Dutch defences were scarcely touched by the raid, and thus remained basically intact. However, the fires started by the bombing in the flammable building stock of Rotterdam’s largely mediaeval quarter soon began to threaten some of their positions and the German troops started to pull back. In the meantime Scharroo, by then totally isolated from The Hague since all communication lines had been destroyed, had to decide the fate of Rotterdam. After the mayor and his aldermen had insisted that the city must be surrendered, the colonel sent them away. He realised that his decision would not only decide the fate of Rotterdam, but possibly that of the whole country. After a brief moment of deliberation, Scharroo made the decision to capitulate, which secured Winkelman’s approval through the presence of his direct representative, Luitenant-kolonel Wilson. Later that afternoon, Wilson conveyed the Scharroo’s decision, which Wilson had sanctioned on behalf of the commander-in-chief, to Winkelman, who concurred.

Accompanied by his adjutant and a senior non-commissioned officer, Scharroo went to the bridges to present the capitulation of the city. He met Schmidt at the bridge and expressed his resentment over the broken word of a German senior officer. Himself surprised by the Luftwaffe action, Schmidt could do nothing but express his own feelings: 'Colonel, I fully understand your bitterness'.

At about 18.00, the first German troops started to work their way through the blazing town. The Dutch troops in Rotterdam no longer resisted but, on Scharroo’s orders, laid down their arms. During the evening, the Germans reached Overschie, where a brief skirmish with a local Dutch unit, unaware of the ceasefire, cost one SS man his life.

Meanwhile, a meeting took place between Backer, who was Scharroo’s official representative, and a German party headed by Student. The meeting was intended to arrange the final details of the surrender. Scharroo had refused to attend, for he was so devastated by the Germans' 'breach of their word of honour; that he refused any further contact with the Germans.

At the same time, a Dutch battalion was assembling for its surrender, as ordered by the Germans. For security reasons, a huge white flag was waved even as an SS battalion was arriving. Seeing so many armed Dutch troops in the square, the SS men started to fire. Student, who had just opened the meeting, ran to the window and about the same time was hit by a bullet in the head and fell, severely wounded though still conscious. It required the skill of a Dutch surgeon to save his life. Student eventually recovered, but he remained hospitalised until January 1941. The German soldiers considered the fact that their general had been shot to be an act of Dutch betrayal, and all Dutch officers, soldiers and even civilians who were present, were lined up by the outraged SS men for summary execution by machine guns positioned in front of them. However, von Choltitz, also present at the meeting, stopped the execution. An investigation was launched, ands this later proved that it had been a stray German bullet that had hit Student.