He said: "The Army have a mix of English and Fijian guys in the side so we are expecting a real open, loose and physical game.
"Last year was a great game in which we used a lot of the young lads, but now a lot of those lads are full-time in the academy so we will be very competitive."
The Cavaliers have tasted plenty of success this season, having won their last four matches. And Hewitt is confident they can continue their good form.
He explained: "We have a long list of talented players. Our youngsters such as Tiff Eden and Andrew Boyce are fantastic.
"But the Army will have a strong side too. They have some Premiership-class players like Ricky Reeves, who will be a constant threat."
The match is in aid of the Help for Heroes charity and the Warriors Community Foundation.
Hewitt added: "Supporting the British Armed Forces is important and it's great to give them an opportunity to play in a stadium such as this.
"It's also great for us to play young lads who are looking to push on from the academy into the first-team."