During World War II, Germany pursued a policy of aggressive expansion that reshaped Europe and triggered a global conflict. The sequence of invasions began with immediate neighbors and extended across multiple continents as alliances and strategic goals evolved.
Understanding the order of these invasions clarifies how Hitler’s regime turned localized threats into a worldwide war. The following sections map the major campaigns in chronological order and explain their lasting impact.
| Invasion | Country | Date | Theater |
|---|---|---|---|
| Fall Weiss | Poland | 1 September 1939 | Western Europe |
| Weserübung | Norway and Denmark | 9 April 1940 | Scandinavia |
| Fall Gelb | Belgium, Netherlands, Luxembourg, France | 10 May 1940 | Western Europe |
| Operation Barbarossa | Soviet Union (Ukraine, Belarus, Baltic states, Russia) | 22 June 1941 | Eastern Front |
| Balkan campaign | Yugoslavia and Greece | 6 April 1941 | Mediterranean |
Invasion of Poland 1939
On 1 September 1939, Germany launched Fall Weiss, a swift combined-arms invasion of Poland from west, north, and south. The campaign utilized blitzkrieg tactics, integrating tanks, air power, and infantry to disorganize Polish defenses within weeks.
The invasion of Poland prompted Britain and France to declare war, marking the official start of World War II in Europe. Despite fierce resistance, Poland was partitioned between Germany and the Soviet Union, demonstrating the effectiveness of coordinated armored and air operations.
Occupation of Scandinavia 1940
Denmark and Norway
On 9 April 1940, Germany executed Weserübung, seizing key Norwegian ports and advancing into Denmark to secure iron ore shipments and naval bases. The operation neutralized potential Allied access to Scandinavian resources and reduced the Royal Navy’s strategic flexibility.
Western Europe 1940
Low Countries and France
Fall Gelb on 10 May 1940 brought rapid thrusts through Belgium, the Netherlands, and Luxembourg to bypass the Maginot Line, followed by a decisive offensive into France. Within six weeks, France requested an armistice, leaving Britain as the sole remaining major power opposing Germany in Europe.
Eastern Front and the Balkans 1941
Yugoslavia and Greece
In April 1941, German forces crushed Yugoslav resistance and overran Greece, ensuring the southern flank before Barbarossa. The Balkan campaign delayed the invasion of the Soviet Union but showcased the risks of multi-front warfare.
Operation Barbarossa on 22 June 1941 directed the largest military force in history into the Soviet Union across a broad front. Initially achieving deep encirclements, the campaign stalled outside Moscow and Leningrad as Soviet logistics and winter warfare offset German momentum.
Key Takeaways
- Germany invaded Poland first, triggering the start of World War II in Europe.
- Scandinavian invasions secured resources and naval positions in 1940.
- The Low Countries and France fell rapidly, leaving Britain isolated.
- Operations in Yugoslavia and Greece preceded the largest invasion in history, Operation Barbarossa.
- Overextension and Soviet resistance ultimately halted German expansion.
FAQ
Reader questions
Why did Germany invade Poland first instead of another country?
Poland offered a strategic corridor to attack France later, provided a pretext to challenge the Treaty of Versailles, and allowed Germany to test blitzkrieg without facing a strong Allied response in 1939.
Which invasion marked the start of World War II in Europe?
The invasion of Poland on 1 September 1939 triggered declarations of war from Britain and France, transforming regional conflict into a world war.
What happened after Germany invaded the Soviet Union?
Operation Barbarossa initially captured vast territory, but Soviet resilience, harsh winters, and stretched supply lines led to a prolonged war of attrition that turned against Germany.
Did Germany ever invade Switzerland during World War II?
No, Switzerland avoided invasion through diplomacy, geographic barriers, and Germany’s reluctance to attack a fortified neutral nation when resources were needed elsewhere.