Sir Winston Churchill (1874-1965) is best known for his leadership of Great Britain during WWII. In the 1930s he tried to warn about Nazi Germany. He became Prime Minister in 1940 after the resignation of Neville Chamberlain. He refused to surrender or compromise in the early days when Britain stood alone in opposition to Adolph Hitler.
He was especially renowned for his broadcasts and speeches. He continued leading as Prime Minister until Nazi Germany was defeated.
You can learn a lot about Sir Winston Churchill on a website dedicated to him.