An elderly war veteran stood guard over his Marine buddy's coffin. He promised to do over 50 years ago after the pair survived the Vietnam War.

Retired Marine Master Sgt. William H. Cox and Marine First Sgt. James 'Hollie' Hollingsworth first met while hiding from rockets and mortars.

On New Year's Eve 1968, just before the dawn of 1969, Master Sgt. William H. Cox and his buddy were holed up in a bunker in Vietnam's Marble Mountains.

Fearing they wouldn't make it out alive, the men—who were strangers at the time—made a pact.

The pact being, "if we survived this attack, or survived Vietnam, we would contact each other every year on New Year's," Cox recalled.

The men made it out alive, and their lifelong promise began.

For the next five decades, Cox and Hollingsworth kept their promise to each other.

As years passed, Cox eventually learned his buddy was terminally ill and made the trip from his home in South Carolina to say goodbye to his dying friend in Georgia.

It was then that Hollingsworth asked Cox to make one final promise—to stand guard over his coffin and deliver the eulogy at his funeral.

Speaking to Greenville Online, Cox recalled:

"I said, 'Boy, that's a rough mission you're assigning me to there.'"

Cox and Hollingsworth completed over 200 helicopter missions together during their time in Vietnam.

According to the Daily Mail, Cox and Hollingsworth ended every phone conversation they made throughout their five-decade friendship with the words:

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

At Hollingsworth's funeral, dressed in Blues, Cox delivered a heartfelt eulogy that concluded with the same words, "Hollie, you keep 'em flying, and I'll keep 'em firing."

The final meeting of the pair was photographed by Cox's son, Bill, who uploaded the image to Facebook with a saying:

"My 83-year-old father, Master Sergeant William H.Cox, USMC, Retired, honoring one of his Vietnam brothers, First Sergeant James J. Hollingsworth (Hollie)."

"They made a pact to stay in touch if they survived their tour, and they did. Both were door gunners, and dad was the only enlisted man in VMO-2 to be awarded the DFC in Vietnam."

"He has to use a cane most of the time now, but he insisted on not using it during his vigil at the casket and at the funeral."

The post has since received thousands of likes and plenty of respect for two outstanding veterans who came together in a time of turmoil.