After six Final Four and five championship game appearances, including two straight losses, the Terps held on for a 9-6 win against Ohio State in the 2017 Division I title game at Gillette Stadium.
Maryland (16-3) last won an NCAA title back in 1975, when Gerald Ford was president, so it was easy to see the relief of the pressure on Tillman's face in the last 30 seconds of the game.
With 22 seconds remaining he finally raised two clenched fists into the air briefly, but quickly went back to coach mode when the Terps lost possession. Then with 16 seconds left, he began hugging assistants, then anyone within striking distance.
"It was certainly a team win," said Tillman, 46, a native of Corning, N.Y. "Wasn't pretty, but I'm certainly proud of how hard they played, and that's been a staple. I'm happy for our state, our school, our students, our alums. Especially the alums having waited so long. I think that was a big thing that motivated us was to try to bring a championship back for them, but also living in the moments, knowing that this was their time."
During the postgame news conference Tillman spent a lot of time talking about the character of his players and complimenting his assistants, but there is no one who deserves more credit than Tillman.
He had the toughest job in Division I lacrosse this season. He had great talent, but it's hard to win a title and coach 18- to 22-year-olds after losing in two previous championship games, including a heartbreaking 14-13 overtime loss to North Carolina last year.
It's even worse when a team is carrying Godzilla on its backs as were the Terps, who hadn't won a championship in 42 years. Maryland had been through some great coaches who couldn't get it done.
Dick Edell was the Maryland coach from 1984 through 2001. He compiled a 171-76 record but failed in three championship appearances. Dave Cottle replaced Edell and had a .625 winning percentage during his nine-year tenure, but his Terps never reached the final.
Tillman got there in his first year, and finally won it Monday.
"I am so proud and excited that the Terps and Coach Tillman are champions," Cottle said. "John has given his heart and soul to Maryland, and I am so happy for him."
So was North Carolina State athletic director Debbie Yow. She took a lot of criticism as Maryland's athletic director when she brought Tillman in to replace Cottle in 2011.
"Bill [her husband] and I watched today, as we have every time the last seven years when Maryland has played in the championship," Yow said after the game. "The last minute was gold. Loved every second. So happy for John and all who have waited so long for this moment."
The title will certainly silence some of Tillman's critics who thought he was overmatched because he came form Harvard and didn't have the pedigree of working in a conference such as the Atlantic Coast Conference, or for former independent giants such as Johns Hopkins or Syracuse.
Some knocked his offense, especially against zones, and of course said he couldn't win the big one. What can they say now?
"No one has been more consistent over the last five years than John Tillman," said Toomey, whose Greyhounds beat Tillman's Terps in the 2012 title game. "He has worked at it, earned it and deserved it. He has done it the right way as far as leadership and teaching his kids the right way."
Actually, Tillman has done it with an approach similar to that of his predecessors. The Terps still play good defense, and on Monday they held Ohio State scoreless for nearly 24 minutes during the game.
"I think that's just how Maryland always is and that's what we try to keep up here," Maryland defenseman Tim Muller said.
Maryland isn't pretty. The Terps have one of the game's top and roughest attackman in Matt Rambo and hardworking midfielders such as Tim Rotanz, Jared Bernhardt, Isaiah Davis-Allen and Matt Neufeldt who just grind opponents down.
Tillman didn't play this style at Harvard, but he has adjusted.
He is a players' coach who lost a bet with them and now has to get a tattoo, but is also smart enough to listen to assistants such as Chris Mattes, the faceoff coach and unsung hero of the weekend. Coaching is a constant evolution, which is why Tillman spends hours reading books on topics ranging from Wall Street to cybernetics.
"So the secret is out. I may get the smallest tattoo in the history of tattoos," said Tillman laughing.
Maybe the best gamble he made was keeping his players away from all the talk about the Terps not winning a championship since 1975. Tillman spoke to them about past failures and learning from them, but he wasn't going to let them get overwhelmed externally.
"He does so much work behind the scenes," Rotanz said. "No one really realizes how much he does. He probably didn't sleep this entire weekend. He puts that much work in. As players, we'll give him a hard time about it and joke about it, but when it comes down to it, if you look at his production as a coach here, the work shows for itself."
As he was about to leave Monday, Tillman talked about how his philosophy wasn't going to change, and his program will continue to be more than wins and losses. He pointed to the team's graduation record, work in the community and helping his players become young men.
Then he said he was lucky to be the coach at Maryland.
And Maryland is thankful to have Tillman.