Churchill served in the British Parliament from 1900.  He was appointed First Lord of the Admirality during World War I.   With the collapse of appeasement, Chamberlain was forced to allow Churchill to enter the cabinet again.  When Chamberlain resigned, in May 1940, Churchill became Prime Minister.  Churchill's courage and determination are considered by many to have been instrumental in rallying the British to fight. Churchill developed a very close working relationship with Roosevelt during the war years.
After the war, Churchill coined the term "Iron Curtain."  After several years out of office, Churchill again became prime minister in 1951, and was knighted in 1953.  In that same year, he won the Nobel Prize for literature.