J. Russell Coffey, the oldest known surviving U.S. veteran of World War I, has died. The retired teacher, one of only three U.S. veterans from the "war to end all wars," was 109.

Coffey died Thursday at the Briar Hill Health Campus in North Baltimore, where he had lived for the past four or five years, said Gaye Boggs, nursing director at the nursing home. No cause of death has been determined, she said Friday. His health began failing in October.

"We're sure going to miss him," Boggs said. "He was our most famous resident, that's for sure."

More than 4.7 million Americans joined the military from 1917-1918. Coffey never saw combat because he was still in basic training when the war ended.

The two remaining U.S. veterans are Frank Buckles, 106, of Charles Town, W.Va.; and Harry Richard Landis, 108, of Sun City Center, Fla., according to the Veterans Affairs Department. In addition, John Babcock, 107, of Spokane, Wash., served in the Canadian army and is the last known Canadian veteran of the war.