"In" isn't a synonym for "during."

Today's New York Times has a story (here) about Richard Blumenthal's exaggerations about his military service.  He apparently didn't serve "in" Vietnam; he served "during" Vietnam.  The Times reports:

In 1970, with his last deferment in jeopardy, he landed a coveted spot in the Marine Reserve, which virtually guaranteed that he would not be sent to Vietnam. He joined a unit in Washington that conducted drills and other exercises and focused on local projects, like fixing a campground and organizing a Toys for Tots drive. 

 There's nothing wrong with serving in a military reserve unit; what's wrong is misstating what one's service record was, especially for personal gain. 

Words matter.