This question is kinda tricky. If you look at it from the surface, it would look as if civilians are indebted to the military men but that is not true.

The military men are the ones indebted to the civilians. The civilians' taxes are what are being used to pay the military men and take care of their needs. So they are the ones indebted to the civilians. Military protect the civilians because the civilians pay them to protect them by paying their taxes.

So they are the ones indebted to the civilians. This is how I see it.