His death, announced by his office, came the day after his family announced he was ending medical treatment on Friday.

He was diagnosed just over a year ago, and has struggled with related health problems ever since.

McCain, who would have turned 82 next week, did not resign his seat after the diagnosis and was a sitting senator at the time of his death.

Back in the Senate, McCain heard the call of war again, as American foreign policy was transformed after the September 11, 2001, terror attacks, and he became a forceful proponent of the US use of force overseas.

He backed US interventions in Afghanistan and Iraq. Even when Americans grew tired of war, McCain warned that more troops were needed, demanding a surge in forces that Bush later adopted.

McCain was elected to the House of Representatives in 1982, before beginning his tenure in the US Senate, where he was re-elected by the state of Arizona five times. McCain lost the GOP’s nomination in 2000 to George W. Bush, before winning the bid in 2008 to run against Barack Obama. He chose Sarah Palin as his running mate in that election—a choice that some, including Obama, have connected to the shift in the Republican party that set the stage for the deeply divided country we see today.

Before his career in politics, McCain—the son and grandson of admirals—served more than 20 years in the US Navy. Nearly six of those were spent in a Vietnamese prisoner of war camp.