This Marine kept a 50-year promise to his Vietnam War buddy

At age 83, Marine Corps veteran William Cox stands and walks with the help of a cane. But for one day in November, 2017, he stood for hours without it, wearing his old uniform. It was the last act of a promise he made in 1968 to his best buddy in Vietnam. That buddy, James Hollingsworth, was laid to rest that day.

Cox is a Vietnam War veteran and retired Master Sergeant. It was New Year's Eve and he and retired First Sergeant Hollingsworth were fortified down in a bunker in the Marble Mountains, just south of Da Nang. From above them, the Viet Cong were raining explosives down on their position. Rockets, mortars, whatever the VC could find. As fiery death pelted their position, they made a promise to each other.

"Charlie was really putting on a fireworks show for us," Cox told the Greenville News. "If we survived this attack, or survived Vietnam, we would contact each other every year on New Years."

And they kept the pact they made in that bunker every year for 50 years. Cox, who lives in Piedmont, S.C., visited Hollingsworth at his Anderson County home just under 20 miles away. But it was another promise Cox made to Hollingsworth that was finally fulfilled one day in late November, 2017 — the retired Master Sergeant stood guard at his longtime friend's funeral as he was laid to rest.

He then delivered his eulogy.

That was also a promise kept, but not one made in Vietnam. When Cox found out his buddy was terminally ill, he made a visit. That's when Hollingsworth made the morbid request of his longtime friend. The two had known each other long before spending that explosive New Year's Eve together in 1968. Their bond as Marines kept their friendship for the rest of their lives.

Hollingsworth, a helicopter mechanic, and Cox, an ordnance chief, served in a helicopter squadron together. At the end of each mission, Cox would deliver Hollingsworth a line he delivered one last time at the end of his best friend's eulogy.

"Hollie, you keep 'em flying, and I'll keep 'em firing."