Their last meeting near the end of the war is referred to as the Yalta Conference. (It was held at Yalta, on the Crimean Peninsula.)
Actually, Stalin was not included in the group of countries that contributed to the nuclear bomb. Churchill did have something with it like Canada and Australia.
Europe could not have had one leader because it was a group of independent countries. If they had had one leader there would not have been a war. Some European leaders were Hitler in the German Empire, Churchill in Britain, Mussolini in Italy, Franco in Spain, Petain in France and Stalin in Russia.
After the Second World War it was clear that the League of Nations (group set up to deal with global humanitarian issues) wasn't working, so in 1945 50 countries signed a charter that set out the aims of what was known as the United Nations Organisation, eventually coming into being on 24th October 1945 (hence why we celebrate United Nations Day on the 24th of October)
After Germany invaded Russia, Stalin joined the Allies (formally known among themsleves as the United Nations). This group expanded over the course of the war, but included Great Britain (and all British colonies and commonwealth nations), the United States, China, Greece, France, Poland, Belgium, Holland, Yugoslavia, and several smaller powers. In general, the term "Allies" was used to refer to the so-called "Big Three" nations - The U.K., America and the Soviet Union. Other nations were granted the status of "Co-belligerent" but not full allies. Examples are Hungary, Italy (after its surrender), Turkey, Persia (Iran) and Iraq.
he relied on others
The Kremlin, and hence the Russian People.
The Ruff Riders
The Rough Riders
The lower classes of wealth ussually supported Stalin. Other than that, it was ussually based on personal opinion (unless there was another significant factor, such as you bolonged to a group targeted by Stalin).
Kulaks
Tennis Cabinet
He targeted the Kulaks.