On May 26, 1940, the British High Command implemented Operation Dynamo, the Allied naval evacuation from Dunkirk, with the first troops, numbering 28,000 being evacuated by ships to southern England on that day. Then the Allies received a stunning blow when on May 27, Belgian King Leopold III asked the Germans for an armistice, and the next day, May 28, 1940, the monarch formally surrendered the Belgian Army. The sudden Belgian capitulation exposed the Dunkirk perimeter’s western flank, seriously jeopardizing the evacuation. However, fierce resistance by 40,000 French troops, the trapped remnants of the French 1st Army at Lille against four German infantry and three armored divisions (comprising 110,000 troops, 800 tanks) stalled the German advance that allowed 70,000 more Allied troops to escape to Dunkirk. But as a result of the 4-day siege at Lille, the French 1st Army was destroyed.
(Taken from Battle of France – Wars of the 20th Century – World War II in Europe – Vol. 6)
The Dunkirk evacuation, lasting from May 26 to June 4, 1940, was successfully carried out: under fierce, constant German air, artillery, and tank fire, and a gradually shrinking perimeter as the Germans broke through the defensive lines, hundreds of small vessels, including privately owned fishing boats and pleasure craft from southern England, were used to assist ships of the British Royal Navy to evacuate Allied troops from the harbor and beaches of Dunkirk. Of the 222 British Royal Navy vessels and 665 other requisitioned boats that took part, 6 British and 3 French destroyers, 24 smaller Royal Navy vessels, and 226 other ships were lost. Also, 19 other British destroyers were damaged, as were over 200 other British and Allied vessels. On June 4, 1940, German forces broke through the last defense line and entered Dunkirk, capturing some 40,000 French troops who had failed to make the evacuation. In total, 331,000 Allied troops were evacuated, of whom 192,000 were British and 139,000 were French. But the British Army left behind all its heavy weaponry and equipment: 700 tanks, 45,000 trucks, 20,000 motorcycles, 2,500 artillery pieces, and 11,000 machine guns.
The German Army now turned its attention to the south, to the conquest of Paris and the rest of France. With 140 divisions (130 infantry and 10 panzer) in a reconfigured Army Groups A and B (and Army Group C inside Germany facing the Maginot Line), the Wehrmacht massed along a 600-mile front along the Somme and Aisne rivers stretching from Sedan to the Channel coast (the French Weygand Line). Facing the Germans were 64 French divisions comprising three Army Groups, including 110,000 French soldiers who had been evacuated in Dunkirk but were repatriated to France via Brittany and Normandy. Also arriving were two other Allied infantry divisions, one British and one Canadian, supplementing one British infantry and elements of one armored division as well as Czech and Polish formations already in France, a combined total of 173,000 troops.
The debacle in Belgium greatly depleted French military resources: France’s best units, comprising over 60 divisions, were lost, as were elite tank formations and a considerable number of heavy equipment and weapons. However, increased moral and resolve swept through the remaining French Army: officers and men were fighting for France’s survival, supply and communication lines were closer, and army commanders and surviving units had gained battle experience. General Weygand implemented a “hedgehog” defense-in-depth network of mutually supporting fortified artillery positions, supported by armor and air cover, aimed at inflicting heavy losses to the attacking German forces.
On June 5, 1940, German forces launched Fall Rot (“Case Red”), the invasion of Paris and southern France, but met fierce resistance at the Somme and Aisne, where their initial attempts to cross the rivers were repulsed with heavy German armored losses. In one instance at the Aisne, a German armored assault lost 80 of its 500 armored vehicles. But with the Luftwaffe’s air superiority being brought to bear, the Wehrmacht established a number of bridgeheads, and armored and infantry units crossed the Somme and Aisne at a number of points. French air attacks failed to destroy the bridgeheads, although the frontline artillery units stalled the German breakthrough for a number of days. By June 9, French air power was waning, and the Luftwaffe soon achieved fully control of the skies. Allied operations also were being greatly hampered by the 6-8 million French civilians clogging the roads as they fled the German advance.
By June 10, 1940, elements of German Army Group B had broken out at Abbeville, Amiens, and Peronne, while General Guderian’s panzers, part of German Army Group A, advanced toward Reims. At Juniville, the French 3rd Armored Division achieved success against the advancing German armor, destroying 100 tanks. However, German armored spearheads across the line continued to advance south.
On June 9, 1940, the French government declared Paris an open (undefended) city, and the next day, it vacated the capital and moved the seat of government to Tours, and later to Bordeaux on June 14. General Weygand also stated that the French Army was on the brink of collapse and that the war was lost. Then on June 10, 1940, Italy entered the fray on Germany’s side by declaring war on France and Britain. Italian leader Benito Mussolini rejected the counsel of his top commanders that Italy was unprepared for war, opportunistically stating that “I only need a few thousand dead so that I can sit at the peace conference as a man who has fought”. Italy’s contribution to the campaign would be inconsequential, as the 450,000 invading Italian troops (outnumbering the 190,000 French defenders by over 2:1) were unable to break through the Alpine Line in the rough, high-altitude terrain and prevailing winter-like snowy weather at the 300-mile long French-Italian border.
Meanwhile, General Rommel’s 7th Panzer Division, advancing down the French coast, captured Le Havre on June 11, 1940, and Saint-Valery-en-Caux, forcing the surrender of 46,000 Allied troops. On June 4, German troops entered Paris without resistance. In the east, Army Groups A and C were tasked with breaking through the Maginot Line, with by now was greatly undermanned, as many of the assigned French armies there had been transferred to other sectors of fighting. Two panzer corps of Army Group A advanced down the rear of the Maginot Line, one taking the towns of Verdun, Toul, and Metz, while the other proceeding to the French-Swiss border to cut off the Maginot Line from the rest of France. On June 15, from the east, Army Group C launched two frontal offensives into the Maginot Line from the Saar region and from the Rhine further south. In these attacks, the Germans used several hundreds of artillery pieces, including giant rail guns that were tasked with breaking down the thick concrete fortifications. The German 1st Army broke through at Saarbrucken, while the German 7th Army breached the Line at Colmar and Strasbourg, forcing the French defenders to retreat to the Vosges Mountains. On June 17, German panzer units reached the Swiss border. Even then, much of the Maginot Line held firm, with 48 of its 58 major fortifications being unconquered by the end of the campaign.
On June 13, 1940 in a Supreme War Council meeting in Tours, the French and British governments acknowledged that the war was lost. As both parties had agreed months earlier that neither side could seek a separate peace with Germany without the other side’s consent, French Prime Minister Reynaud now asked Prime Minister Churchill to allow France to be released from this commitment. Churchill refused, and instead proposed a political union between the two countries (Anglo-French Union) and the French government and military transferring France’s seat of power to its colonies in North Africa where they would continue the war. Both proposals were rejected by the French government, and on June 15, Reynaud resigned as Prime Minister, and was succeeded by World War I hero, Marshall Philippe Petain, who immediately made a radio broadcast indicating his intention to seek an armistice with Germany.