also a promise to withdraw from Iran within six months of the war's conclusion (these assurances later proved essential in securing his country's independence after the war). In September 1943, the Shah went further, and he declared war on Germany. He signed the Declaration by United Nations entitling his country to a seat in the original United Nations. Two months later, he hosted the Tehran Conference between Churchill, Roosevelt, and Stalin. The presence of so many foreign troops in Iran accelerated social change and it roused nationalist sentiment in the country. In 1946, Hossein Gol-e-Golab published the nationalist song Ey Iran; it was reportedly inspired by an incident during the war in which Golab witnessed an American GI beating up a native Iranian greengrocer in a marketplace dispute. Strategic need for supply to the USSR After the British were pushed off the continent, Germany was essentially without any opposition in Europe until Hitler launched the invasion of the USSR in June 1941. In order to relieve pressure off the Soviets, British and American leaders sought to open a front in the West to engage the German military. Realizing this goal could not be immediately achieved however, the western Allies made the strategic decision to provide Stalin with material support at levels substantial enough to ensure that the Red Army could continue to engage the bulk of the German military. The allies established protocols that defined the type and amount of material that would be delivered in a given time frame. However German military action on the Arctic route, coupled with the fact it could not be traversed during the winter, prevented the US was from meeting the first protocol. This caused increasing pressure on the Allies to develop the route using the Persian Corridor. Supply efforts The Allies delivered all manner of materiel to the Soviet Union ranging from Studebaker US6 trucks to American canned food. Most of the supplies transiting through the Persian Corridor arrived by ship at various ports in the Persian Gulf and were then carried northwards by railroad or in long truck convoys. Some goods were later reloaded on board ships to cross the Caspian Sea and others continued their journey by truck. The United States Army forces in the corridor were originally under the Iran-Iraq Service Command - later renamed the Persian Gulf Service Command (PGSC). This was the successor to the original United States