Shelby Fetsch was excited to throw out the ceremonial first pitch at the Cardinals game on May 25 in St. Louis -- which was dedicated to Americans serving in the military -- but she ended up getting the surprise of her life.

After Fetsch's pitch, Fox Sports Midwest reports, the catcher quickly peeled off his mask, revealing himself to be Army Specialist William Johanson, 22 -- Fetsch's boyfriend, who she thought was in Afghanistan.

But as soon as 20-year-old Fetsch expressed her joy at Johanson's unexpected return, she got another surprise -- a proposal at home plate.

"I love you, and I want to spend the rest of my life with you," said Johanson, who is serving with the 463rd Military Police Company, before getting down on one knee and proposing to Fetsch in front of the 43,375-person crowd.

Fetsch accepted, and the stadium went wild.

"He did it big and it will be the most memorable moment of my life," Fetsch told St. Louis local news station KSDK.

The couple told KSDK that they plan to marry next summer. They expect to start planning their Big Day together in six months, after Johanson finishes his service in Afghanistan.