I had a brother at Khe Sanh fighting off the Viet Cong
They're still there, he's all gone

from Bruce Springsteen – Born in the U.S.A. Lyrics on Rap Genius

Meaning

This line about the narrator’s literal or figurative “brother” (the word is changed to “buddy” in some live performances) contains a minor mistake. The Vietnam War’s Battle of Khe Sanh did not pit U.S. forces against the Viet Cong. Instead, they fought the North Vietnamese Army. The U.S. won, but withdrew a few months later. That battle thus here becomes a stand-in for the futility of the entire war effort

The line “they’re still there, he’s all gone” implies that his buddy died in vain in the jungles of Vietnam, as the U.S. ultimately exited the war with little to show for the countless deaths.

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