Cold War Timeline By cassandratrejo06 Aug 4, 1945 "Little boy" was dropped on Hiroshima Aug 9, 1945 "Fat Man" was dropped on Nagasaki Period: 1947 to 1991 Cold War began and ended Mar 12, 1947 Truman Doctrine 1949 NATO was formed Oct 29, 1949 Soviets dropped their nuclear bomb 1950 Berlin was divided Divided into communist east berlin and democratic west berlin Nov 1, 1952 Enewetak was dropped Nov 12, 1953 Soviets dropped their thermonuclear bomb May 14, 1955 Warsaw pact was formed Oct 4, 1957 Sputnik-1 was launched Jan 31, 1958 The explorer was launched 1961 Berlin Wall was built Period: 1989 to 1990 Belin Wall came to an end 1991 Soviet union dissolved into component republics