In the thread "Charedim and the army", R' Josh Backon wrote:
> War is required in what's termed a "Milchemet Mitzva"
> and is permitted in what's termed a "Milchemet Reshut".

This is totally accurate, of course, and I really can't argue with 
it. But I reminds me of a question which I've had for a long time, 
and might even have asked on these pages, but with little or no 
response, so I'd like to ask it again.

What is the rationale behind a milchemes reshus?

In the past, this chevra has discussed various ways in which the 
Torah permits activities which modern sensitivities consider wrong 
and sinful. Most notably, slavery, but I think we've talked about 
others too.

It seems to me that a Milchemes Reshus is not only in this category, 
but may be even far worse than slavery. After all, even in a worst-
case scenario, one cannot kill his eved. In contrast, in a milchemes 
reshus, we are killing members of the other nation, and we are 
putting our own selves in deadly danger.

And for what purpose? To increase our territory? If our melech wants 
the extra territory because he feels threatened and needs more secure 
borders (as in 1967) one could argue that it is a milchemes *mitzva*. 
The milchemes *reshus* situation sounds like he wants extra territory 
merely for reasons of prestige. Why are we not offended by this 
concept?

Akiva Miller