Ryan Parent stepped down as manager of the Tiffin Saints following Saturday's doubleheader with the Ohio Travelers.
Parent said his decision was one centered on personal and professional reasons, along with his service in the United States Marine Reserves.
"We might get an order to deploy," he said.
"I need to head back and spend time with the family," Parent said.
Parent soon will receive a promotion, moving from staff sergeant to gunnery sergeant by mid-July.
He leaves a team sitting in first place in the Independent Baseball League at 13-9 after splitting the doubleheader with the Saints (11-11).
Saints owner Brian Dutton said he's sorry to see Parent go, but understands why.
"He's been a close friend from the beginning. Ryan's been very close with the organization. He's helped plan most the season, all the player personnel decisions," Dutton said. "He's been a loyal friend, and I hate to lose him but he has military coming up.
"I hate to lose him," he said. "He's a great guy; very, very loyal to the organization. Helped us get through some rough patches."
Dutton added he hopes Parent can return to work with the team next year.
Calvert baseball coach Dustin Ritchie will take over running the Saints for the rest of the season.
Parent said he felt the Saints will be in good hands with Ritchie, while Dutton said Ritchie's familiarity with the team will help with the transition.
"He's worked with Ryan for most of the summer. He know the player personnel, he knows the players in the league," Dutton said. "He's a knowledgeable baseball guy. He just seemed like a logical choice."