I tried an early warrior rush in BTS at Noble level. Moved 4 warriors to an AI city with 2 warriors and attacked the next turn. My first warrior died but inflicted 1.2 health damage, an ok start. My second warrior did no damage before perishing. But what the F? Suddenly there are 3 AI warriors in the city. How can this be? Is the game not as "turn-based" as I thought? Is this another unsuspected AI bonus--the ability to materialize units in the middle of a battle? I have been playing Civ on and off for years but have never seen this before.