Jonathan Philip Yeager (b. 1943) was conceived on the wedding night of Sam Yeager and Barbara Larssen Yeager in Chugwater, Wyoming during the Race Invasion of Tosev 3. The couple was passing through Chugwater with the United States' atomic bomb program, which had been forced to abandon the University of Chicago some months earlier when Chicago fell to the Race. Barbara's pregnancy led her to remain with Sam after she discovered that her first husband, Jens Larssen, was still alive. Jonathan was born during the war against the Race, and accompanied his parents across wartorn American territory to wherever Sam's services as an emerging expert on the Race and as the guard responsible for Ullhass and Ristin.