Thomas, 92, and his brother Robert, 88, enlisted in 1944. They were sent in separate directions -- Thomas served in the Army Air Forces in Germany, while Robert went west on the USS Hyman and the Battle of Iwo Jima.
On Wednesday, two days before the 70th anniversary of Victory in Europe Day, the Mets reunited the brothers.
"The Mets are dedicated to honoring our nation's active duty and retired military personnel, and it was a special privilege to host two brothers who served in World War II," the club said in a statement.
The brothers, both natives of Queens, hadn't seen each other in about a year. But in the third inning, they stood side by side as their faces graced the scoreboard screen and received a round of applause from the 21,667 in attendance. Jon Niese and Anthony Recker presented them with folded American flags.
"I always wanted one," said Thomas, who still wears a stainless-steel bracelet emblazoned with AAF wings around his wrist. "This is amazing."
Thomas grew up a Brooklyn Dodgers fan, and he remembers being excited when the expansion Mets came to Queens in 1962.
Robert is a former mounted NYPD officer who loves listening to baseball on the radio.
"They were surprised to be honored," said Vin Vergara, Thomas' grandson. "It was truly a stunner for them."
War brought the brothers their share of not-so-pleasant surprises, with Robert surviving an attack during the Battle of Okinawa that killed 12 of his shipmates.
In all, five members of the Moldenhauer family served during the war.
"And all of us were in combat," Thomas said. "All of us made it back. It's incredible."