In 1939, a group of senior German Army officers, including Erich von Manstein and Franz Halder, devised a plan to inflict a major defeat on the French Army in northern France. The Manstein Plan, as it became known, included a attack through southern Belgium that avoided the Maginot Line. The ultimate objective was to reach the Channel coast and to force the French government to surrender.

Adolf Hitler gave his approval to the Manstein Plan on 17th February, 1940, but it was not activated until the 10th May, when the Luftwaffe bombed Dutch and Belgian airfields and the German Army captured Moerdijk and Rotterdam. Fedor von Bock and the 9th Panzer Division, using its Blitzkreig strategy, advanced quickly into the Netherlands. Belgium was also invaded and the French 7th Army moved forward to help support the Dutch and Belgian forces.

The 7th Panzer Division under Erwin Rommel and the 19th Corps commanded by Heinz Guderian and the 6th and 8th Panzers led by Gerd von Rundstedt, went through the heavily wooded and semi-mountainous area of the Ardennes, an area, north of the Maginot Line. The French military had wrongly believed that the Ardennes was impassable to tanks. Seven panzer divisions reached the Meuse River at Dinant on 12th May and the following day the French government was forced to abandon Paris.

German forces led by Paul von Kliest, Erwin Rommel, Heinz Guderian and Gerd von Rundstedt advanced towards the Channel. Except for a counterattack by 4th Armoured Division led by Charles De Gaulle, at Montcornet (17th May) and Laon (27th-29th May) the German forces encountered very little resistance.

Winston Churchill now ordered the implementation of Operation Dynamo, a plan to evacuate of troops and equipment from the French port of Dunkirk, that had been drawn up by General John Gort, the Commander in Chief of the British Expeditionary Force (BEF). Between 27th May and 4th June, 1940, a total of 693 ships brought back 338,226 people back to Britain. Of these 140,000 were members of the French Army. All heavy equipment was abandoned and left in France.

General Maxime Weygand, the Supreme Allied Commander, tried to hold the line along the Somme and the Aisne. Now clearly outnumbered, the French Army was forced to withdraw to the Loire. The Germans occupied Paris on 14th June and two days later, Paul Reynaud, the French prime minister, was replaced by Henri-Philippe Petain, who quickly accepted German peace terms.

Under the terms of the armistice northern France and the regions north of Vichy came under German occupation. The French government, led by Henri-Philippe Petain, moved to Vichy and remained at liberty along with the French Navy and an army of 100,000 men.

During the defence of France nearly 2 million French soldiers were taken prisoner. An estimated 390,000 soldiers were killed defending France whereas around 35,000 German soldiers had lost their lives during the invasion.