Balkans campaign (World War II)
On the 28th of October 1940, Italian troops crossed into Greece, setting off a chain of events that would consume the entire Balkan peninsula within seven months. That single act of aggression did not unfold as Benito Mussolini planned. Instead of a quick victory, Italy found its armies driven backward into Albania, its winter line holding only about two-thirds of that territory. Adolf Hitler watched Italy's failure and made a decision that would redraw the map of southeastern Europe. By the 1st of June 1941, every country in the region - Albania, Yugoslavia, and Greece - was under Axis control. What drove this cascade? How did a botched Italian invasion become one of the largest and most consequential military operations of the war? And what price did Germany pay for winning so decisively?
Albania's story before the war explains why Italy could launch its Greek invasion from there at all. After World War I, the collapse of the Ottoman and Austro-Hungarian empires left Albania searching for protection. At the Paris Peace Conference in 1919, United States President Woodrow Wilson blocked a European plan to divide Albania among its neighbors, preserving the country's territorial integrity. That reprieve did not last.
From 1925 onward, Mussolini worked to dominate Albanian affairs. In 1928, Albania became a kingdom under Zog I, a former clan chief and Prime Minister. Zog could not hold back Italian influence in his country's internal life. On the 7th of April 1939, Italian troops invaded, overthrew him, and formally annexed Albania to the Italian Empire. When Italy crossed into Greece the following year, it did so from Albanian soil it already controlled.
Italy's October 1940 invasion of Greece made initial gains before the Greeks reversed the advance and pushed the Italians back to the Albanian border. Throughout that winter, Italy worked to stabilize a line that left it holding roughly two-thirds of Albania. The United Kingdom supported Greece with the Royal Air Force during this period, though British and Commonwealth ground forces were tied up in North Africa and could not arrive quickly.
A major Italian offensive in March 1941, one that had been widely anticipated, produced almost no territorial gain. It was a failure that settled the question of whether Italy could win this fight on its own. On the 23rd of April, Greece officially surrendered to both Italy and Germany - but only after Germany had intervened directly. The Italian 9th and 11th Armies pursued retreating Greek units back toward the mainland, while Greek forces fought rearguard actions that slowed but could not stop the advance.
Hitler began planning an invasion of Greece in November 1940, after British forces occupied Crete and Lemnos. He signed the order for the operation - code-named Unternehmen Marita, or Operation Marita - on the 13th of December 1940, originally scheduling it for March 1941. The stated purpose was to prevent Britain from placing air bases close enough to strike the Romanian oilfields, which Germany depended on.
A coup in Yugoslavia on the 27th of March 1941 changed the timeline. Hitler ordered the conquest of Yugoslavia as well. On the 6th of April, Germany invaded northern Greece simultaneously with its assault on Yugoslavia. German forces broke through Yugoslav lines in southern Yugoslavia and used that corridor to send reinforcements into northern Greece. They out-flanked the Greek Metaxas Line fortifications, moved south through the country, and entered Athens. The Battle of Greece ended with the fall of Athens and the capture of the Peloponnese. Roughly 40,000 Allied soldiers were evacuated to Crete before the mainland was lost.
The operation against Yugoslavia, known as Operation 25, began on the 6th of April 1941. Hungary joined the invasion on the 11th of April. The Royal Yugoslav Army signed an unconditional surrender on the 17th of April - eleven days after the fighting started.
Germany and Italy then rebuilt the territory according to their own interests. They created the Independent State of Croatia, known by its Croatian initials NDH, by combining Bosnia and Herzegovina, parts of Croatia, and Syrmia. In the territory of the former Kingdom of Serbia and the Banat, Germany appointed a puppet government called the Government of National Salvation, led by Milan Nedic. Montenegro went under Italian occupation. Bulgaria received permission to annex eastern areas, including most of what is now North Macedonia. The old Kingdom of Yugoslavia was gone.
On the 20th of May 1941, German paratroopers dropped over the airfields of northern Crete. Allied forces and the local Cretan population resisted fiercely, but the defenders were eventually overwhelmed. The British Government ordered an evacuation on the 27th of May. All remaining forces surrendered on the 1st of June.
The price Germany paid for Crete was significant enough to change its strategy for the rest of the war. The paratroopers suffered such heavy losses that the Supreme Command of the Wehrmacht decided to abandon large-scale airborne operations permanently. Operation Merkur - the assault on Crete - stands as one of the largest airborne attacks in the history of warfare, and it was also the last of its kind for Germany.
Bulgaria officially joined the Axis Powers before the April 1941 campaigns but chose not to participate in the invasion of Yugoslavia or the Battle of Greece when they began on the 6th of April. On the 20th of April, the Bulgarian Army moved into most of Western Thrace and the Greek province of Eastern Macedonia - territory that Germany had already conquered. Bulgaria's goal was to restore its pre-World War I access to the Aegean Sea. Bulgarian troops also occupied much of eastern Serbia, where the Vardar Banovina region was divided between Bulgaria and Italy.
The occupation arrangement gave Bulgaria significant territorial gains without the cost of the initial fighting, and it held those gains for the remainder of the war in the Balkans.
Germany's rapid victory came with a long tail. Active resistance movements in Yugoslavia, Greece, and Albania forced the Axis to permanently garrison hundreds of thousands of soldiers across all three countries. Those troops were denied to other fronts for the duration of the war.
After 1943 in Yugoslavia, the threat of an Allied landing combined with partisan activity required large-scale counter-insurgency operations involving several divisions. The resistance movements that emerged from the occupation would shape the political character of the region well beyond the war's end, and the borders drawn in 1941 - the NDH, the German military territory in Serbia, Bulgaria's annexation of North Macedonia - each carried consequences that extended far past the moment of Germany's strategic triumph.
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Common questions
When did the Balkans campaign of World War II begin and end?
The Balkans campaign began on the 28th of October 1940 with the Italian invasion of Greece and ended on the 1st of June 1941 when the last Allied forces on Crete surrendered. By that date, all of Albania, Yugoslavia, and Greece were under Axis control.
Why did Germany invade Greece in World War II?
Hitler ordered the invasion of Greece, code-named Operation Marita, on the 13th of December 1940 primarily to prevent Britain from establishing air bases close enough to strike the Romanian oilfields. Germany also intervened to rescue Italy, whose invasion of Greece had stalled and been reversed by a Greek counter-offensive.
What happened to Yugoslavia after the Axis invasion in 1941?
The Royal Yugoslav Army surrendered unconditionally on the 17th of April 1941, eleven days after the invasion began on the 6th of April. Germany and Italy dissolved the kingdom and created several successor entities, including the Independent State of Croatia (NDH), a German puppet government in Serbia led by Milan Nedic, Italian occupation of Montenegro, and Bulgarian annexation of most of modern-day North Macedonia.
What was the Battle of Crete and why was it historically significant?
The Battle of Crete began on the 20th of May 1941 when German paratroopers were dropped over the airfields of northern Crete. The remaining Allied forces surrendered on the 1st of June. It ranks as one of the largest airborne operations in the history of warfare, but German paratrooper losses were so severe that the Wehrmacht's Supreme Command abandoned large-scale airborne operations for the rest of the war.
What role did Bulgaria play in the Balkans campaign of World War II?
Bulgaria had officially joined the Axis Powers but did not participate in the 6th of April 1941 invasions of Yugoslavia and Greece. On the 20th of April, the Bulgarian Army moved into Western Thrace and the Greek province of Eastern Macedonia, territory Germany had already conquered, aiming to restore Bulgaria's pre-World War I access to the Aegean Sea. Bulgaria also occupied much of eastern Serbia and held these territories for the remainder of the war.
How did Italy come to control Albania before the Balkans campaign?
On the 7th of April 1939, Italian troops invaded Albania, overthrew King Zog I, and annexed the country to the Italian Empire. This followed years of Italian interference in Albanian affairs under Mussolini dating from 1925, and it gave Italy the territory from which it launched its 1940 invasion of Greece.