With outfielder Peter Bourjos bound for three-day paternity leave after the birth of his first child, the Cardinals called up 29-year-old reliever Mitch Harris to join their roster for Tuesday’s game against the Nationals in Washington.

Harris comes with an interesting backstory: He is a graduate of the U.S. Naval Academy, the first to ascend to the big-league ranks since Nemo Gaines made four appearances out of the Washington Senators’ bullpen in 1921.

The right-hander was drafted in the 13th round in 2008 and hoped to receive an assignment that would allow him to pursue pitching professionally. But with the country at war, Harris’ request was denied and he spent nearly five years on active duty — including drug-patrol tours in South America and two trips to the Middle East — before getting his discharge in early 2013. When he arrived to Cardinals camp that year, he told Derrick Goold of the St. Louis Post-Dispatch about preparing for a baseball career in the Persian Gulf:

While at sea, Harris did what he could to keep his arm in shape. He always packed a glove. His dad shipped him new baseballs in care packages…. A few baseballs left behind in the Persian Gulf are his. “I’d go out and throw with one of the guys and just think, ‘I’m in the middle of the Persian Gulf preparing to play baseball.’” Harris said. “Here I am surrounded by water, can’t see land, the ship is moving a little bit. But it was this kind of mentality: If I don’t, then I won’t.”

Harris made his professional debut in Class A ball later that year and sped through the Cardinals’ system, reaching Class AAA Memphis by the end of the 2014 season. He begins his Major League career with a lifetime 2.78 ERA in 94 innings across 66 minor league appearances.