who said "he had but one life to live for his country"

Nathan Hale is credited with saying this before being executed by the
British in 1776 at the age of 21:

"Nathan Hale, American Revolution Patriot: The Connecticut Society of
the Sons of the American Revolution have complied a detailed history
of Connecticut's State Hero, who had but one life to live for his
country."

Eastern Connecticut State University: The American Revolution
http://www.ecsu.ctstateu.edu/depts/edu/textbooks/revolutionarylinks.html

The quote is found in several variations, including the following:

"I only regret that I have but one life to give for my country." 

Hyperdictionary
http://www.hyperdic.net/dic/H/Hale.shtml#n09032045

"I only regret that I have but one life to lose for my country." 

Nathan Hale Institute
http://www.nathanhaleinstitute.org/bio.asp

"My only regret is that I have but one life to live for my country." 

The Road to Revolution: America's Fight for Freedom
http://www.epd86.org/flashanddash/studentpage.html

"I only regret that I have but one life to live for my country."

American Patriots: Nathan Hale
http://www.sd84.k12.id.us/Farmin/revwar/nathanhale.htm

My Google search strategy:

"one life to give for my country"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=%22one+life+to+give+for+my+country

"one life to lose for my country"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=%22one+life+to+lose+for+my+country

"one life to live for my country"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=%22one+life+to+live+for+my+country

I hope this is the information you're looking for. If anything above
is not clear, please request clarification before rating my answer.

Best regards,
pinkfreud

"I only regret that I have but one life to give for my country."

Thank you pinkfreud. It was exactly what I was looking for! I
appreciate your help. God bless,

albertarose