The Second World War is usually considered to have begun with the German invasion of Poland on 3 September 1939 though one can trace the sequence of events back to the German invasion of Czechoslovakia on 15 March 1939 and the British and French pledge to support Poland on 29 March. The war spread to the Pacific with the Japanese attack on Pearl Harbour on 7 December 1941.
The war in Europe ended on 8 May 1945 (VE Day) when the Germans signed the official surrender that had been offered the previous day. The war in the Pacific ended with the decision on 14 August 1945 and the announcement by the Emperor of Japan in a broadcast to his people on 15 August 1945 (VP day) that Japan would accept the Allies ultimatum to surrender. The formal surrender to General Douglas MacArthur in Tokyo Bay followed on 2 September (VJ Day). I hope this is the right answer, if it's not i'm sorry
Like the Roman government, the United States has a tripartite system. The U.S. system of checks and balances makes sure that one branch of the government doesn't have too much power. This system is like the veto, which limited the power of Roman consuls.
