Who was the president in 1917?

This depends on the country/organization. See related questions.

US: Woodrow Wilson.

Woodrow Wilson was the 28th President of the United States from 1913 March 4 to 1921 March 4. Although he initially kept the US out of the World War in his first term, the US joined the war in his second term. He is also known for his creation of the League of Nations after the war.