Germany, as we all know, started rearming in secret under the restrictions of the Treaty of Versailles. In 1931 a twin engined cargo plane pottered down the runway, it later became the Heinkel 59 float plane. Destined to be used by the German Navy for a variety of roles, this twin engined design was never going to set the world on fire. It had fuel tanks in its floats, fixed pitch propellers and two horribly underpowered engines. To give you an idea, it couldn't out run a World War One era fighter. On the plus side it was a very stable aircraft.
However suddenly a situation arose in the planning of Fall Gelb that suddenly gave the humble HE-59 a centre stage in world events.
HE-59 float plane
The issue was Holland. In the centre of Rotterdam runs the river Nieuwe Maas and the seizure of the bridges over the river was of importance to the German plans. With the Dutch prepared for war they might have time to demolish the bridges before the German forces could reach them. With this in mind a plan was drawn up, a tiny force of German airborne infantry was to land crammed into twelve of the ancient HE-59's. On the outbreak of war these twelve planes would chug slowly into Holland, land on the Nieuwe Maas and the troops would then inflate rubber boats, load the boats with their weapons, ammunition and equipment and paddle to shore capturing the Willemsbrug and Spoorbrug bridges. The latter was a railway bridge close by to the Willemsbrug road bridge.
The two bridges
The Royal Dutch Air Force had several hundred armed aircraft each with about three times the speed of the German planes. If the Germans had been attacked they'd have been unable to fight, and unable to run, and been hacked out the sky. To make matters worse the river had plenty of 20mm AA gun emplacements.
All the soldiers involved practised unloading from the cramped HE-59's on a German lake until in the early hours of the 10th of May 1940, they put the plan into action. At 0450 the planes arrived over Rotterdam, and swept down onto the water, landing in a wedge. An unknown number were damaged in the landing. No enemy action had been encountered so the troops quickly unloaded and began to paddle for the banks. Once at the banks the Germans started to struggle up the steep sides, laden by their weapons and equipment. However some helpful Dutch civilians thinking it was an exercise helped the soldiers ashore. The German soldiers behaved impeccably towards the civilians. The civilians were interested in this strange occurrence and crowded around the German soldiers. This proved to be a hindrance as the Germans tried to move to capture both ends of the bridges. Eventually the civilians were ordered out of the way at gunpoint. With the bridge secured and no explosive found the soldiers started to set up a roadblock, then a unit of Dutch police appeared and tried to prevent the Germans blocking the traffic. Three were killed and the rest taken prisoner.
The actual landing opperation
As the Germans tried to expand the Dutch forces began to respond. Sending out patrols armed with an LMG they began to slowly force the Germans bridgehead to constrict. With attacks from all directions fierce fighting began. What's more remarkable is these attacks by the Dutch forces were carried out with none of the commanders communicating with any of his allies. Yet they seemed to be perfectly timed.

Then as the day wore on a new threat appeared. Two Dutch naval vessels approached, a Motor Torpedo Boat with a pair of 20mm cannons, and a larger coastal patrol boat with a pair of 75mm guns and a pair of heavy machine guns. In order to save the bridge the MTB was to use its 20 mm cannons to clear the bridges, while the larger ships cannon were to smash any German forces around the bridges. As they took a pounding from the centre of their position the beleaguered Germans suddenly got some welcome news, one side of their perimeter had linked up with the main German force! First some machine guns arrived and began to take the naval vessels under fire, the smaller MTB was unarmoured so stayed in the lee of the larger ship, to protect itself from the hail of machine gun bullets.
The Dutch MTB, named TM-51
Then the AA gun emplacements along the river bank opened up, a single Ju-88 Stuka swept overhead and planted a stick of four 250 kg bombs into the river aimed at the coastal patrol boat. They missed, but the force of the explosion lifted the MTB out the water and knocked out one of its engines, as well as causing structural damage. The MTB pulled out. The coastal patrol boat carried on fighting until it had emptied its magazines and also had to withdraw.

As the German bridgehead was linked up more forces began to move into the area until the river bank was in German hands, but the opposite side was still in Dutch hands. Now you have the situation that lead to the Rotterdam blitz...

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