Who is Mark Fossie? What does he do?

Mark Fosse is a medic. He brought his girlfriend to Vietnam.

Later in the night, though, a young medic named Mark Fossie kept coming back to the subject.

"Look, if you think about it," he said, "it's not that crazy. You could actually do it."
"Do what?" Rat said.
"You know. Bring in a girl. I mean, what's the problem?"
Rat shrugged. "Nothing. A war."
"Well, see, that's the thing," Mark Fossie said. "No war here. You could really do it. A pair of solid brass balls, that's all you'd need."
There was some laughter, and Eddie Diamond told him he'd best strap down his dick, but Fossie just frowned and looked at the ceiling for awhile and then went off to write a letter.
Six weeks later his girlfriend showed up.

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