Combat in Ceasar 4 is about the same as in Caesar 3: not very detailed.
Frankly, the whole Caesar series are city builders, not wargames. The rule book states that you have chosen to be a Governor, not a General, and you only use Troops to defend your cities. IF you want detailed game on Roman warfare, looks somewhere else. "Pretorians" of "Great Battles"..both at gog....are more up your alley.
Sorry for answering late. I lost track of my own thread. :S
I was thinking about if it was a RTS clickfest mess or more hands off combat. Too intensive combat would be annoying for me in a mainly city building game.