So as the defender you bring in 2 reinf 2nd wave. The attacker doesn’t like the odds and has no eligible units to reinf so he retreats. The defender would then have to pull his 2 reinf units back and they would be idle for 1 complete round? Sounds like a good bluff and you might hold on to the country. Keeping track of idle units might be hard, because you could end up with several nations with idle units causing some confusion. Don’t get me wrong I like the idea of the defender having options for reinforcements or retreat. I think its silly to think the defender would just sit there and let the enemy dictate the battle with out using all his resources. Maybe someone else will chime in with an idea or two.