Cobbled this from imdb:

Served in the United States Navy during WWII

Was an active participant in the battle of Tarawa (Nov. 1943), one of the bloodiest battles of World War II, and U.S. Marines Corps history. Is credited with braving enemy fire during 26 rescue missions saving wounded Marines. Was awarded the Bronze Star with a combat 'V' for rescuing 70 Marines during the battle of Tarawa in 1943
Has spoken about it in television documentaries.

Because of his his early work with environmental causes and groups, when International Earth Day was created, it was decided it must be held on April 22 because that is his birthday.