Elsewhere in the Fortress Holland
In Rotterdam the local fights between the Dutch troops and the German air landing troops continued for the third day. Although the Dutch didn't regain control over the bridges, the Germans were suffering from continuous assaults on their positions. Not any rest was given to them and they had a hard time re-supplying their troops.
Especially the Dutch marines had proven themselves tough and determined adversaries to the Germans and it didn't fail to leave some impression on the latter. Still, casualties mounted up at both sides and the German command grew increasingly worried over the state and status of their troops in the heart of Rotterdam.
The third day of the war was the last day that Waalhaven was used by German transport planes. It were mainly supplies that were flown in.
At Spijkenisse bridge a battle was fought between a small Dutch force and Germans of IR.72, a reserve unit of the 22.LL.ID that had been provided from the regular 46th Infantry Division. The battle ended undecided. The Dutch stayed in control of the Spijkenisse bridge and even expanded the occupation of the Oude Maas river banks.
Delft and Overschie
To the north-east of Rotterdam, at the village of Overschie [nowadays part of Rotterdam], the remnants of both air landings at Ockenburg [about 350 men] and Ypenburg merged into a quite impressive force.
General Graf von Sponeck had very cunningly moved the remainder of his force from Ockenburg to Overschie, smartly negotiating his way between Dutch forces in the area. Only in the small village of Wateringen - where the Dutch had a command post - the Germans bumped into a guard squad of the Dutch and when two armoured cars appeared to support the Dutch defenders, the Germans backed-off and took a detour. The clash between the two sides was quite intense though, leaving three Germans and six Dutch dead on the scene. The Von Sponeck formation succeeded however in reaching the village Overschie, where it joint up with the already present Germans of the forces that had survived the Ypenburg battle. The General took command over the combined forces that amounted over 750 men by then.
The Dutch probed the German defences around Overschie a number of times, but time and again in vain. Especially an attempt at the southside of Overschie [at the current zoo Blijdorp] ended quite bloody for the Dutch. Nine men perished. On the German side the losses are unknown due to unspecified mortality lists. One men is specifically identified as KIA in Overschie on the 12th. Many KIA from the vicinity are listed under Rotterdam, Delft or Ypenburg though.
At Valkenburg the Dutch kept pounding the village with artillery fire. Especially the centre of the village suffered from this shelling and nearly all houses sustained some degree of damage from this relentless pounding. The fighting was much less intensive than the days before.
Limitations from the top
Dutch counter measures against the German strongholds left much to be desired. The Commander Fortress Holland had ordered his subordinate commanders not to undertake any action beyond company size. This very peculiar order had found its origin in the fact that the GHQ still expected additional air landings and required the remaining troops of the 1st Corps to remain intact and at direct disposal. Larger scale actions would cause troops involved to jeopardize their state of readiness.
The side effect of this very questionable order was that the Dutch siege-forces around Valkenburg and Overschie did not have the authority to launch large scale assaults, let alone coordinated actions from more directions. A very unfortunate situation. It would mean that both German strongholds would remain in place - hardly without any serious challenge - until the overall capitulation of the Dutch forces at the 14th.
Panic in the north
At some point the impression had grown that the German cavalry forces in the northeast would rather sooner than later manage to cross the IJsselmeer and land north of Amsterdam to the rear of the Dutch defences. Although there was not a single German that had dared to to offshore from the Friesland coast, the thought of such event able to occur, already triggered counter measures.
Troops in the vicinity of Amsterdam and Haarlem were ordered to prepare improvised defences along the Noordzee canal [that ran from Amsterdam to Ymuiden, into the Northsea]. Posts were set out along the west-shore of the IJsselmeer. Not a single German appeared of course.
A new defence-line
In the Hague the GHQ had started thinking about an improvised defence-line cutting the Fortress Holland into two parts. They seriously considered the options should the Rotterdam front yield and German troops push over the Nieuwe Maas into the Fortress. Overnight [12/13 May] - when it became obvious that a German army with considerable tank forces were indeed on their way north - the plans were fixed to organise a new anti-tank defence along the cities of The Hague and Leiden all the way to Amsterdam.
By the time the defence-line was ordered to come into place, the idea of renewed airlandings had been waivered. The actual German strategy had become apparent. The airlandings had mainly been executed to facilitate the ground forces an open entrance into the tough nut called Fortress Holland. It were mainly the troops of the 1st Corps that were used to man the defence-line. It would take some time yet to have it shaped and manned all along. It was a clear sign that the Dutch would not give up their resistance once the Germans would have been able to penetrate into the actual Fortress.
Several transports of German POW's to IJmuiden (harbour) were ordered by General Winkelman on the 12th. The POW's came from all front-lines in the country. Many of them were Luftwaffe personnel of downed planes, airbornes and airlanding troops. Only very few others. In the early morning of the 13th the SS Phrontis would steam out of the harbour of Ymuiden and reach the UK later that day, with 1,011 POW's on board. On board were many experienced and senior German military who would remain in POW camps in the UK and Canada for the duration of the war.
Ymuiden was also the harbour where Princess Juliana and Prince Bernhard left for the UK in the late evening. The Prince would later return to the Netherlands, where he would visit the Dutch troops in Zeeland.