The shorter one (Ancyra) took about a week, the longer one (Rome) took around 2.
Of course, that was the only action happening during the turn, so it wasn't an inconvenience to take that long.
-edit- Actually, those aren't good examples to use, really. These were massive battles (equivalent of 4 stacks for Ancyra and 5 & change for Rome) and in Rome's case, lots of coordination was required. Here each side has approximately 5/6 of a stack and, as econ already mentioned, he's modifying the turn system to make it shorter.
-edit again- All this WotS talk makes me feel like an old man. "Back in my day we had real Civil Wars! With over five stacks and the fate of Republics at stake! None of this namby-pamby, two-turn, two-stack, battle over Duchies stuff! Bah!"
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