The answer lives in this podcast
What was the Manstein Plan and how did it trap the Allied forces in May 1940?
General Erich von Manstein designed a two-pronged deception: send forces visibly through Belgium to draw the Allies forward, then strike the real blow through the Ardennes Forest — terrain so steep and densely wooded that no one expected tanks to cross it. The Allied armies surged into Belgium exactly as planned, exposing their flank. Hitler threw the bulk of the Wehrmacht through the Ardennes, creating a breakthrough the Allies had never anticipated and could not stop.
Belgium as the bait — and why the Allies took it
On May 10, 1940, German forces swept into the Netherlands and Belgium. To French and British commanders, this looked like a replay of World War I: a German thrust through the Low Countries, exactly the direction the Maginot Line was designed to force. France had spent enormous resources building that 280-mile fortification system along the German border, confident it sealed off any direct assault.
That confidence had a dangerous side effect. France positioned its best troops — and the British Expeditionary Force of approximately 300,000 men, described as the cream of British ground troops — along the Belgian-Dutch border, ready to push forward and meet the Germans head-on. As Tom Hanks recounts in World War II with Tom Hanks, this was precisely what Hitler wanted them to do.
Manstein understood that a predictable German attack through Belgium would be met by a prepared Allied army. So he kept that Belgian thrust alive — just not as the main effort. It was a feint on a national scale.
The Ardennes: the gap no one thought to guard
The Ardennes Forest, stretching across southern Belgium and Luxembourg, was widely considered impenetrable — too steep, too wooded, too narrow for a modern armored advance. Allied planners largely dismissed it as a viable axis of attack. Manstein bet everything on that assumption being wrong.
While Allied armies were surging north into Belgium toward the distant rumble of gunfire, the Wehrmacht's main armored force was threading through the Ardennes in a column that stretched back for miles. When it broke out into open France, there was nothing meaningful in its path. The episode explored in this podcast makes clear that the Allies had not just been outfought — they had been outthought from the start.
The breakthrough created a massive pocket. More than 450,000 French, Belgian, and British soldiers found themselves cut off and pushed toward the English Channel. The trap had closed completely by May 20, 1940, as detailed in the "Blitz" episode of World War II with Tom Hanks.
"We shall fight on the beaches. We shall fight on the landing grounds. We shall fight in the fields and in the streets. We shall fight in the hills. We shall never surrender."
Spoken in the immediate aftermath of the Allied collapse in France — a direct response to the catastrophe the Manstein Plan had produced.
That defiance came after the fall, not before it. The Manstein Plan had already done its work. Understanding the full strategic collapse that made those words necessary is something World War II with Tom Hanks covers with striking clarity across the "Blitz" episode.
See also
How did Nazi ideology shape Hitler's treatment of Jewish people and Slavic populations in occupied Poland?
Hitler's worldview was based on a neo-Darwinian biological struggle between races, with the Aryan race — the Germans — destined to rule Europe. In occupied Poland, this translated into systematic persecution of Jewish people and Slavic populations deemed racially inferior.
What was American public opinion and official policy toward the war in Europe at the outbreak of World War II in 1939?
When Americans were polled on whether the United States should get involved, 90% said absolutely not. The peacetime army was small, and neutrality laws made direct intervention politically and legally very difficult.
What role did Winston Churchill play at the outset of World War II and why did Roosevelt seek him out rather than Chamberlain?
Churchill was appointed First Lord of the Admiralty and joined the new war cabinet after war was declared, having spent the 1930s as Hitler's most vocal critic. Roosevelt saw in Churchill the resolve and clear-eyed understanding of the Nazi threat that Chamberlain lacked.
Key takeaways
- The Manstein Plan was built on deliberate deception: a real but secondary thrust through Belgium masked the true attack through the Ardennes.
- The Ardennes was considered impenetrable by Allied commanders — Manstein's plan exploited that blind spot directly.
- Allied forces, including the 300,000-strong British Expeditionary Force, advanced into Belgium and were encircled from behind by the Wehrmacht's armored breakthrough.
- By May 20, 1940, over 450,000 soldiers were trapped and retreating toward the beaches of Dunkirk — the direct consequence of the plan working exactly as Manstein designed.
The full story of how the Manstein Plan unfolded — and what came next — is covered in the "Blitz" episode.
Listen to the episode on Listenly