Fontane continued his busy performance schedule throughout the 1960s and into the early 1970s, even traveling several times to Vietnam to sing for American troops stationed there. He also performed for four U.S. Presidents—Dwight D. Eisenhower, John F. Kennedy, Lyndon B. Johnson and Richard M. Nixon. But his life began to unravel in 1973 when he was diagnosed with prostate cancer and given only a year to live. Despite undergoing several unsuccessful operations, he continued to sing. Four days before his death, he went to an Orange County, California, church where two men—one on each side of him—helped stand him up for his last concert. He sang "Just As I Am". Two days later, his pancreas ruptured, and he was rushed to a Canoga Park hospital.