During World War II, Allied forces launched the Italian Peninsular campaign in September 1943 after their successful invasion of Sicily and the Italian coup against Benito Mussolini.
Following World War I, the Italian Fascist Party leader Mussolini and his Blackshirts aggressively controlled Italy, several major islands of Greece, and parts of Africa, including present-day Libya and Ethiopia. In 1936, Mussolini created the Roma-Berlin Axis with Hitler, and in 1941, Italy joined Germany and Japan as an enemy of the Allied forces, namely France, England, Russia, and the United States.
Though he was adept at political maneuvering, Mussolini proved to be a poor military leader, and World War II quickly went badly for Italy. Much of its African empire was soon lost to the British, and Mussolini was forced to accept German assistance. By the spring of 1942, morale among the population was falling as a result of defeats and growing food shortages. The loss of the Axis armies in North Africa in May 1943 spelled the end of Italy's empire.
On July 10, 1943, the Allied forces launched the Sicily invasion. Mussolini continued to lose favor among the near starving Italian people, and on July 25, Victor Emmanuel III, the king of Italy, had Mussolini arrested during the Italian coup. For the next 45 days, Italians demonstrated against the war until Italy surrendered to the Allied forces and declared war on Germany.
Meanwhile, the Allies began invading the Italian mainland, beginning with the "heel" of Italy on September 2, 1943. The landing took the Germans by surprise, and the Allied forces were able to capture two good ports, Taranto and Brindisi. On September 3, the Allies invaded Calabria, the "toe" of Italy, but progress was slow, as the terrain was rough and only two good roads ran up the coast. Allied forces then landed on the "shin" of Italy at Salerno, just south of Naples, on September 9. They were met by disciplined German forces under Albert Kesselring and did not take Naples until October 1.
The Germans fell back from their positions near Naples, and Kesselring consolidated the German hold on central and northern Italy. The Nazis brutalized the northern Italians, which in turn fortified the Italian Resistance against the Germans. For a short time, things looked bad for the Allied forces; the Nazis rescued Mussolini from his prison and set him up as a puppet leader while they held off Allied forces and continued to brutalize the Italians under their control. Autumn and midwinter passed without the Allies making any significant headway against the Germans' Gustav Line, which ran for 100 miles from the mouth of the Garigliano through Cassino and over the Apennines to the mouth of the Sangro.
On January 22, 1944, the Allies attempted to bypass the Gustav Line by landing some 50,000 troops and 5,000 vehicles at Anzio, only 33 miles south of Rome. However, they met with stiff German resistance during the Battle of Anzio and were bogged down for several months along the coast. U.S. troops under Gen. Mark Clark finally entered Rome in May 1944, but Kesselring established strong lines north of the city and held them back for nearly a year. It was not until the spring of 1945 that the Germans were finally driven out of Italy and into southern Austria.