Will my units be the attacker or defender?

Question

In a game I have ROW with another player and they have planted troops in 2 of my territories. I also have troops in these territories. He has gone inactive and it is now time I get rid of him. My question is if I declare war and we both have troops in the same city and they automatically engage, in MY territory, who would the attacking stack belong to? I have ATs and Inf and he has mainly LTs so I would like the defensive stack of course but afraid even tho its in my territory if I declare war I will be the initial attacker.

Any one with the answer?

*added

I should state that I have him outmatched completely with artillery RRGs and airforce as well, so I'm not worried about losing whatsoever, but would like to save as many troops as possible and without losing the territories upgrades in the skirmish.

Update:

I believe my troops did end up as the defensive stack. His went troops went instantly on the attack circle countdown and mine remained on all black and said "attacked by" in the activity section.. even tho I declared war and hit him with everything I had at range.