The Second World WarAfter the First World War Germany and his new lider, Adolf Hitler wanted revenge with the nations that had won the war and decided to carry out his expansion programme. Before to occupy Austria in 1938, the Fuhrer stipulated a non-aggression pact with the USSR. When Hitler invaded Poland in 1939, France and Great Britain declared war upon Germany. Hitler, in the summer of the same year attacked France and on 14th June proceeded to Paris. In the winter of 1942 Germany dominated Europe and attacked the USSR. The only European country who fought against German troops was Great Britain. The United States took part to the war when, on 7th December 1941, Japan attacked the American naval base at Pearl Harbour. On 6th June 1944 the Allies Anglo-American landed in Normandy, on the northern coasts of France. The German troops was gradually defeated and had to retreat. On April 25th 1945 the Italian partisans drove the American troops out of Italy. On May 8th Germany was compelled to surrender. To stop Japan the USA dropped two atomic bombs on the Japanese tows of Hiroshima and Nagasaki. On 2nd September Japan surrendered too. This horrifying war caused the death of 50 million people and a lot of damage. In February 1945 the victorious nations held a congress at Yalta to discuss the post-war issues. After the Second World War the USA and the USSR became the greatest powers in the world and confirmed their economic and political supremacy. Europe was dived into two different blocks: the socialist countries, under the leadership of the USSR, and the capitalist countries, under the influence of the United States. Germany was divided into two different states and in 1961 a wall was built in Berlin to separate East from West. The western European countries together with Canada and United States signed the North Atlantic Treaty. They created a new political and military alliance called NATO while the socialist countries formed an alliance called the Warsaw Pact.