Turn 11, May 6, 1940
Germany Declares War on the Netherlands! – In a lightning stroke Germany crushed the Netherlands in a matter of days. Germany infantry armies first destroyed the main Dutch Army. Then Armor destroyed the Dutch air force on the ground and the Dutch Headquarters in their capital of The Hague. Last, German Armor sank a Dutch light cruiser on the docks. All Dutch military forces in Europe excepting one destroyer which got away were eliminated.

Only after Dutch forces were crushed did Germany declare war on Belgium. Sequencing these declarations of war allowed armor forces to occupy the Hague. Otherwise, the zones of control by Belgian forces would have prevented knocking the Netherlands out of the war in one move. Belgium moved 90% towards the allies and would have joined them the following turn.
German forces then moved into Belgium occupying Maastricht and Liege.

The United States (28%) and the USSR (7%) moved toward the allies in response.
Elsewhere, a previously purchased sub was launched by Germany and the British took control of Iceland. Allied naval forces continued their disruption of Norwegian imports.
Turn 12, May 28, 1940
Germany destroyed several units and captured Brussels. I’m unsure if they can hold it against allied counter-attacks since it is only occupied by a corps. During these attacks the Belgian airforce was destroyed by a combination of infantry attacks and straifing.

British Strategic Bombers hit two Dutch cities mere days after they fell to the Germans. Those Brits are nice chaps to their former allies!

Germany completed research in Command & Control.