On this day in 1940, the Luftwaffe mounted its first air raid on the Belgian capital, Brussels.

On this day in 1940, just 24 hours before the German army was scheduled to begin a major new offensive in the West, British and French troops moved into Belgium over the protests of the Belgian government.

The Belgians quickly changed their tune about the Anglo-French presence, however, when they learned that their country was among those targeted by the upcoming German offensive..

On this day in 1940, Belgium declared war on Nazi Germany as the Wehrmacht invaded Holland.

On this day in 1940, RAF bombers attacked Berlin in retaliation for the previous day's German air raid on Brussels.

On this day in 1940, British, French, and Belgian troops entered Holland to stop the Nazi invasion of that country.                                                                                                    

On this day in 1940, a contingent of British Royal Marines landed on the Dutch coast to relieve the besieged British army pocket at Tillburg.

On this day in 1940, the German army in Holland trapped two British divisions near Tilburg.

On this day in 1940, the German army launched a counterattack against the Royal Marines beachhead near Tillburg.

On this day in 1940, Hitler ordered Luftwaffe paratroopers to assault the British pocket near Tillburg.

On this day in 1940, Belgium's King Leopold III made a radio broadcast rejecting German demands for his nation's surrender and calling on his fellow Belgians to "fight until our last bullet has been fired and our last bomb dropped". Just hours after this speech, Allied tanks assaulted the German left flank near Tillburg.

On this day in 1940, the German front near Tillburg collapsed under constant pressure from Allied infantry and armored units.

On this day in 1940, Wehrmacht panzer commander Erwin Rommel, a veteran of the previous autumn's Polish campaign, was killed when RAF fighters strafed his command car while he was leading a relief force to break besieged German troops out of a cul-de-sace near the town of Maaseik.

On this day in 1940, German resistance at Maaseik collapsed.

On this day in 1940, RAF bombers attacked southern Germany in Bomber Command's most devastating air raid up to that time in the war in Europe; dubbed the "1000-bomber raid" because at least a thousand bombers were involved in the operation, the attack struck war industry plants and military installations throughout Germany's south-western regions.

The air strikes couldn't have come at a worse time for the Third Reich, whose Belgian offensive was on the verge of collapse and whose toehold in Holland was in grave jeopardy.

On this day in 1940, what was left of the German expeditionary force in Belgium surrendered to the British army.

In Holland, Dutch anti-Nazi partisans shot and killed Reichskommissar Artur Seyss-Inquart and hanged Dutch fascist leader Anton Mussert for treason; these events marked the beginning of a larger rebellion against German occupation forces that was still underway when Allied troops began advancing into Holland two days later. Click to read the entire Belgium 40 thread

On this day in 1940, Allied ground forces entered Holland with only minimal resistance from the Wehrmacht; with German occupation forces in Holland preoccupied by the Dutch anti-Nazi uprising it took nearly 36 hours for Wehrmacht troops to begin their counterattack, and by then British and French artillery units were within shelling range of German defensive positions outside Rotterdam and Eindhover.

On this day in 1940, British and French troops in Holland eliminated the last pockets of German resistance in Rotterdam and liberated Amsterdam after only token opposition by the Wehrmacht.

The loss of Amsterdam in particular enraged Adolf Hitler, who sacked four of his top generals on the spot and demoted two others for "incompetence". By contrast the leader of the British expeditionary force, Lieutenant General Bernard Law Montgomery (pictured), was elevated to the rank of field marshal for his skillful use of Allied ground forces against the Germans.

Montgomery would later serve as Allied commander-in-chief for land forces in the Mediterranean, where his victorious Libyan offensive would help hasten the overthrow of Italy's Fascist regime.

On this day in 1940, Luftwaffe paratroopers began a desperate 11th-hour offensive in Holland in hopes of salvaging the German armed forces' crumbing fortunes there; the operation proved to be a catastrophe, however, as Allied intelligence agents behind the German lines had tipped British and French commanders off to the impending assault 36 hours earlier, giving Allied ground forces time to set an ambush for the paratroopers.

80 percent of the paratroops committed to the offensive were killed or wounded, making one of the worst defeats ever sustained by a German battle force in any war. News of the disaster drove Luftwaffe paratrooper corps commander-in-chief General Kurt Student to shoot himself the next day.

In a two-page suicide note found in his office shortly after his death, Student ruefully observed his men had gone "a bridge too far" in their efforts to salvage the German front in Holland. In the official announcement of Student's death, however, Nazi propaganda minister Joseph Goebbels claimed the general had been killed leading his troops in a flank attack on the Allied lines.

On this day in 1940, BBC Radio announced that Allied infantry and tank units had crossed the Dutch border into Germany.