* One of the most outspoken and prominent pacifists during World War I.
* Wrote and published numerous pamphlets, articles, and books critical of the war.
* Served a six-month prison sentence in 1918 for publishing an anti-war pamphlet.
2. Jane Addams (United States)
* A leading pacifist and social reformer who co-founded the Jane Addams Hull-House in Chicago.
* Served as president of the Women's Peace Party and was awarded the Nobel Peace Prize in 1931 for her peace efforts.
3. Romain Rolland (France)
* A prominent French writer and intellectual who was a lifelong pacifist.
* Wrote several anti-war essays during World War I and refused to take up arms for the French army.
4. Carl von Ossietzky (Germany)
* A German journalist and pacifist who was awarded the Nobel Peace Prize in 1935 for his work in exposing Nazi Germany's rearmament program.
* Served a prison sentence in the 1930s for his anti-war activities.
5. Bertha von Suttner (Austria)
* An Austrian pacifist and writer who is best known for her novel "Lay Down Your Arms" (1889), which was a powerful indictment of war.
* Served as president of the International Peace Bureau and was awarded the Nobel Peace Prize in 1905.