John McCain, the onetime Navy pilot and longtime lawmaker, was among the best known veterans in America, and has arguably been the most influential and consistent military advocate for the Republican party for the last three decades. (Stephan Savoia/AP)
Lt. Cmdr. John McCain III, 30, right, shown in 1967, is a member of a famous U.S. Navy family and served as an aircraft carrier pilot. His father, John S. McCain Jr., center, served as the Navy's commander in chief in Europe. His grandfather, left, Adm. John S. McCain, commanded all U.S. aircraft carriers in the Pacific during World War II. (AP)
John McCain, front right, poses with his squadron in 1965. McCain has been awarded the Silver Star, Bronze Star, Legion of Merit, Purple Heart, Distinguished Flying Cross medal and the Prisoner of War medal. (Library of Congress via AP)
John McCain is administered to a Hanoi, Vietnam, hospital as a prisoner of war in the fall of 1967. McCain spent 20 years in the U.S. Navy, a quarter of it in a Vietnamese POW camp after his jet was shot down over Hanoi during an Oct. 26, 1967, bombing mission. (AP)
Lt. Cmdr. John McCain is welcomed by U.S. President Richard Nixon on May 24, 1973, in Washington, D.C., upon McCain's release from a POW camp during the Vietnam War. (Getty Images)
Rep. John McCain, R-Ariz., holds a photo of a marker in Hanoi at Truc Bach Lake where he parachuted after being shot down as a Navy pilot in the Vietnam War. He was elected to the U.S. House of Representatives in 1982. (Jim Bourdier/AP)
U.S. President George W. Bush, right, listens after endorsing Republican presidential candidate John McCain in the Rose Garden of the White House on March 5, 2008. McCain had lost to Bush for the presidency in 2000. (Jim Watson/AFP via Getty Images)
Sen. John McCain, R-Ariz., left, greets veterans who were in the audience after delivering a speech at the National World War I Museum on April 7, 2008, in Kansas City, Mo. (Mary Altaffer/AP)
Republican presidential candidate Sen. John McCain, R-Ariz. left, speaks during a debate with Democratic presidential candidate Sen. Barack Obama, D-Ill. McCain lost the general election to Obama in 2008. (Mark Wilson/Getty Images)
Sen. John McCain, R-Ariz., greets Afghanistan war veteran Sgt. Luke Cifka on Capitol Hill on Dec. 9, 2014. McCain was heavily involved in veterans policy and reforming the Department of Veterans Affairs. (J. Scott Applewhite/AP)
Sen. John McCain talks with Air Force Lt. Col. Karl Weinbrecht at Bagram Airfield, Afghanistan, on July 4, 2015. (1st Lt. Michael Mortellaro/U.S. Air Force)
Sen. John McCain’s death removes one of the few remaining Vietnam-era veterans from national elected office, a fact that the senator lamented in a CNN interview in spring 2017. He said he hoped the next generation of service members from the Iraq and Afghanistan wars could help rekindle civil debate on Capitol Hill. (J. Scott Applewhite/AP)
Sen. John McCain returns to the Senate accompanied by his wife Cindy on July 25, 2017, in Washington, D.C. McCain had been diagnosed with brain cancer but returned on the day the Senate held a key procedural vote on U.S. President Donald Trump's effort to repeal and replace the Affordable Care Act. (Win McNamee/Getty Images)
Sen. John McCain, R-Ariz., chairman of the Senate Armed Services Committee, laughs while trying to put on his gift, a Navy bathrobe, after addressing the Naval Academy on Oct. 30, 2017, in Annapolis, Md. He spoke about the importance of American leadership and service to one's country. (Astrid Riecken/Getty Images)
On Dec. 1, 2017, Sen. John McCain, R-Ariz., left a closed-door session where Republican senators met on the GOP effort to overhaul the tax code. President Donald Trump announced McCain was returning home to Arizona after being hospitalized over the side effects from his brain cancer treatment. (J. Scott Applewhite/AP)