There was no single leader during WW1. Each country had their own leader.
He was like a leader in the WW1 or WW2 (world war one or world war two) and he was the one, the leader of britain there was a leader for france very much like him.
Benito Mussolini.
Spain's dictator Francisco Franco kept his country out of World War 2 by declaring neutrality.
Italy
Britain.
The united states of America
Spain.
Of Germany
Prime Minister Winston Churchill, was the leader of Britain and inspired his country during the war.
The United Kingdom.
It was his country fighting in the war. Germany was fighting and he felt like his country needed a strong military leader