It started in a fit of jealous pique. It ended in the German conquest of Yugoslavia, Greece and the Eastern Mediterranean. It arguable affected the biggest military operation in history. And it was never intended to happen.
It started in the latter part of 1940. Benito Mussolini, Fascist Dictator of Italy was feeling out of sorts. The man he had regarded as his junior partner before the war, Adolf Hitler, was now master of Europe from the Atlantic to the Bug, and from the North Cape to the Mediterranean. And he had the bad habit [from Mussolini's point of view] of not informing his Italian ally of intended moves ahead of time. On top of that, Italy had not exactly covered itself with martial glory since joining the war on June 10th, 1940. The Italian attack on France stalled within a few miles of the Franco-Italian border. Mussolini's invasion of Egypt had sputtered to a halt at Mersa Matruh. The British were liberating Ethiopia and Somalia. In short, Mussolini' sun was in eclipse, and he didn't like it. So he cast about for an Italian war he thought he could win. Since his foreign policy had always considered the Balkans his sphere of influence, his eyes fell on Greece. Thinking a strike from Albania [annexed in 1939] would garner him the prize he sought, Mussolini ordered an invasion with almost no planning. And he didn't inform Hitler of the move until it was underway.
Adolf Hitler had neither the desire, nor intention of getting militarily involved in the Balkans. He had bigger fish to fry, the fish being the Soviet Union. And he also had a Balkans Achilles heel, the Ploesti oil fields of Rumania, his principal source of oil for this armed forces. So concerned was he that, by mutual agreement with Rumania's dictator, Marshal Ion Antonescu, Luftwaffe air units, AAA units, and ground troops had been deployed to protect the oil fields. And so concerned was he, that he sought to contain the Balkans diplomatically. Bulgaria joined the Tripartate Pact. Rumania was an ally. Hitler set about wooing Yugoslavia, and made substantial progress. And then Mussolini invaded Greece.
The British, of course, offered Greece aid. It included promises of ground, naval and air units. That meant, from the German point of view, bombers in range of Ploesti. And still German intervention might have been avoided if the Italian Army had quickly overrun Greece before the British intervened. It didn't happen.
The Italians attacked in Greece's western mountains, in the worst of weather, with poorly led, equipped and organized troops. The Greeks not only stopped the Italians, they invaded Albania. At that point, German intervention in Greece was no longer a question of 'If', but 'When'.
Hitler had cards to play. Units from Army Group South for "BARBAROSSA" were switched to Bulgaria for an invasion of Greece. Hitler's diplomatic efforts with Yugoslavia seemed to bear fruit, with the government acceding to German requests for troop transit through the country to Greece. Then the wheels fell off. The British appeared in Greece. British agents fomented a coup that overthrew the pro-German government, and refused the Germans' troop transit. Hitler was enraged, ordered Yugoslavia conquered, and Belgrade destroyed. With some adjustments to the ops plans, that's what happened.
On April 6th, the Luftwaffe destroyed Belgrade with intensive bombing. The German army rolled in from the northwest, north and east, on their way to Greece. The Yugoslav Army, wracked by obsolescence and dissension [Croatian units deserted en masse, resulting in Croatia becoming an independent Fascist state], was carved up in short order, and the Germans drove south into eastern Greece.
The German campaign in Greece, Operation Marita, was highlighted by the Germans battling Australian and British troops at Thermopolye, German airborne troops seizing the isthmus of Corinth, and the Germans capturing Athens. The Greeks and British Commonwealth troops then withdrew to Crete, leading to Operation MERKUR [MERCURY], the German airborne assault on Crete. The Germans took such heavy losses, Hitler never used his airborne troops in airborne operations again. They also took Crete, inflicted major losses on the Royal Navy, and sealed their dominance in the Eastern Med. And Poesti remained safe for several more years.
The results [aside from the above]? Churchill, in an extremely shortsighted move, stripped his forces in the Libyan desert [the British had taken all of eastern Libya from the Italians up to El Agheila], leading to Rommel's first offensive, which would drive the British back to Egypt [except for the garrison at Tobruk]. Mussolini was again forced to ask for German help in another Italian theater of war-North Africa.The war in Africa would run two more, unnecessary years [Churchill would do the same thing in late 1941, pulling troops from Africa to go to Singapore, to surrender to the Japanese-and leading to Rommel's second offensive.
Hitler was now stuck with garrisoning several Balkan possessions he didn't really want, requiring not only ground troops, but some naval, and fairly major air units [coastlines, Royal Navy]. And then there was BARBAROSSA.
In histories written shortly after World War II, PUNISHMENT, MARITA and MERKUR were fixed as the cause for the German failure in the Soviet Union, claiming the delay of some six weeks campaigning time cost the Germans any chance of success. Since then, that view has fallen out of favor. A particularly wet Spring in the western Soviet Union would have prevented the Germans from attacking any earlier than two weeks than they did. But the Balkans offensive did cause wear and tear to the equipment and men from Army Group South used in the attack. And aside from combat losses, the manpower allocation for BARBAROSSA, already thin, was stretched thinner by the requirement to garrison both Yugoslaiva and Greece [garrisons that would grow and bleed off German troop strength as partisan war flared and expanded].
And it all started because of one man's wounded vanity and thirst for glory.
