Key facts and dates

The period from September 1939 to June 1940 was a critical phase in the early stages of World War II, marked by initial inactivity on the Western Front followed by rapid German military successes. This timeline captures the pivotal events that shifted the balance of power in Europe during this time.

Timeline of key events

• September 1939 – Britain and France declare war on Germany but launch no major offensives, beginning the Phoney War.
• November 1939 - March 1940 – Soviet Union expands into Baltic states and fights Finland in the Winter War.
• April 1940 – Germany invades Denmark and Norway to secure resources and strategic positions.
• May 1940 – Germany launches a blitzkrieg through the Low Countries and Ardennes, bypassing the Maginot Line.
• Late May - Early June 1940 – Dunkirk evacuation rescues Allied troops from advancing German forces.
• 10 June 1940 – Italy enters the war on Germany's side as France nears collapse.
• 22 June 1940 – France signs an armistice with Germany, marking its rapid defeat.

The Phoney War: Inactivity on the Western Front

When Britain and France declared war on Germany in September 1939 following the invasion of Poland, there was an expectation of immediate conflict. However, the Western Front remained eerily quiet for several months, a period dubbed the 'Phoney War' or 'Sitzkrieg' (sitting war). Despite mobilising their forces, the Allies did not launch any significant offensive to aid Poland, which fell to German and Soviet forces by October 1939.

Reasons for Allied inactivity

• Hope for economic pressure - Britain and France believed that a naval blockade would cripple Germany's economy over time, reducing the need for immediate military action.
• Avoiding the Siegfried Line - Germany's heavily fortified western border, known as the Siegfried Line, deterred direct attacks due to the high cost in lives and resources such an assault would entail.
• Planning for attrition - Allied leaders anticipated a long war of attrition, similar to World War I, and focused on building up their forces and resources rather than engaging in early offensives.
• Political hesitation - There was a lingering hope among some leaders that a negotiated peace might still be possible, further delaying aggressive military strategies.

Soviet expansion in the East

While the Western Front remained stagnant, the Soviet Union was active in the East, capitalising on the Molotov-Ribbentrop Pact, a non-aggression agreement signed with Germany in August 1939. This pact included secret protocols dividing Eastern Europe into spheres of influence, enabling Soviet territorial gains.

Soviet actions during the Phoney War

• Occupation of the Baltic states - Between September and October 1939, the Soviet Union forced Estonia, Latvia, and Lithuania to accept military bases, effectively bringing them under Soviet control by mid-1940.
• Winter War with Finland - From November 1939 to March 1940, the Soviet Union invaded Finland, seeking territorial concessions. Despite fierce Finnish resistance, the conflict ended with the Moscow Peace Treaty, ceding significant Finnish territory to the USSR.
• Contrast with the West - While Britain and France remained passive, Soviet aggression in the East highlighted a stark difference in approach, reshaping the geopolitical landscape and alarming neighbouring states.

German invasions of Denmark and Norway (April 1940)

The Phoney War came to an abrupt end in April 1940 when Germany launched sudden invasions of Denmark and Norway. These operations marked the beginning of active military campaigns in Western Europe and showcased Germany's strategic planning.

Motivations for the invasions

• Strategic objectives - Germany sought to secure vital iron ore supplies from Sweden, transported through Norwegian ports, and to prevent British interference in Scandinavia by establishing naval and air bases.

Outcomes of the invasions

• Rapid conquest of Denmark - On 9 April 1940, Denmark was overrun in a matter of hours, offering little resistance due to its small military and proximity to Germany.
• Campaign in Norway - Also beginning on 9 April, the invasion of Norway faced more opposition, including Allied attempts to support Norwegian forces. However, by June 1940, Germany had secured control, though at the cost of significant naval losses.
• Impact on the Allies - These invasions exposed Allied unpreparedness and forced Britain and France to divert resources, weakening their position as Germany prepared for its next move.

The revolutionary campaign in the West (May 1940)

In May 1940, Germany unleashed a devastating military campaign in Western Europe, employing a strategy known as blitzkrieg (lightning war). This approach combined rapid armoured advances with air support, catching the Allies off guard and leading to dramatic results.

Key stages of the German offensive

1. Invasion through the Low Countries - On 10 May 1940, Germany invaded Belgium, the Netherlands, and Luxembourg, drawing Allied forces northward to defend these territories.
2. Breakthrough in the Ardennes - Simultaneously, German armoured divisions advanced through the Ardennes forest, a region considered impassable by the Allies, outflanking the heavily fortified Maginot Line along the French-German border.
3. Rapid advance and encirclement - German forces split Allied armies, trapping British and French troops in a pocket near the coast. This led to the evacuation of over 300,000 soldiers from Dunkirk between late May and early June 1940, a desperate but crucial operation to save Allied manpower.
4. Fall of France - With their defences shattered, French resistance crumbled. Paris fell on 14 June, and on 22 June 1940, France signed an armistice, effectively surrendering to Germany after just six weeks of fighting.
5. Italian entry into the war - On 10 June 1940, as France teetered on the brink of defeat, Italy declared war on the Allies, hoping to gain territory and align with Germany's apparent success.

Features of blitzkrieg tactics

• Speed and coordination - Combined use of tanks, infantry, and air support to achieve rapid breakthroughs and disrupt enemy lines.
• Surprise and deception - Attacking through unexpected routes like the Ardennes to bypass strong fortifications.
• Psychological impact - The sheer speed of advance demoralised opponents, preventing effective counter-strategies and leading to swift capitulation.

Significance of the campaign in the West

The events of May and June 1940 reshaped the course of World War II, demonstrating the effectiveness of German military tactics and altering the European balance of power. The rapid collapse of France had profound strategic and political consequences.

Major impacts of German success

• Peak of blitzkrieg - The campaign showcased blitzkrieg tactics at their most effective, proving that modern warfare could achieve decisive results in weeks rather than years of trench warfare.
• Collapse of France - France, considered a major military power, fell in just six weeks, overturning assumptions about a prolonged conflict and exposing Allied strategic flaws.
• Britain stands alone - With France defeated, Britain remained the only major European power resisting Germany, facing the threat of invasion and intensifying pressure to continue the fight.
• Hitler's dominance in Western Europe - Germany's control over much of Western Europe solidified Hitler's position, making him appear invincible and shifting the focus of the war.
• Encouragement of further expansion - This unprecedented success boosted Hitler's confidence, encouraging ambitious plans for further conquests, including the eventual invasion of the Soviet Union in 1941.

These early victories set the stage for a broader conflict, as Germany's rapid gains forced the Allies to rethink their strategies and brace for a prolonged struggle against Nazi domination.