They're playing the game Saturday at Lincoln Financial Field, and that means both the Army and the Navy have already invaded Philadelphia.
It's that time of year again, just one day before the big game. The festivities began early in Center City, and so did the competition.
"For the past 8 or 9 years the Navy's been here, we always came out on top. And I guess today's whole-in-one competition is just a precursor to what's going to happen tomorrow," said Russell Mainor.
But this deep-seeded rivalry and family tradition isn't just about who comes out on top.
"At the end of the day, we're all still brothers in arms, serving our country. But even brothers fight from time to time," said Mainor.
It's a day of pride for the vets who still show their enthusiasm.
And for those who never made it to a game. Dee Thiesmeyer came all the way from Pasadena California in honor of her late army father.
"This is his ID bracelet with his serial number on it from the military. So he's here with me," said Dee Thiesmeyer.
Come tomorrow about 70,000 people are expected to fill Lincoln Financial Field to witness one of the biggest rivalries in all of college football. Who will win this year's bragging rights? We'll have to wait and see.