I like your repository idea. It would not be hard to erect a building or monument for these ashes. I even like your word: it could be called “The Repository of the Services”.
It would hold ashes of anyone from any service.
How about...
The Repository of the American Will and Dedication to a Free World.
Memorializing the remnants of our service members in connection to such a lofty goal, would seem almost unavoidable.