My succesful attack owed as much opportunism, and to my good and plentiful attacking units, as it does to any grand plan. If there had been a few more Infantry, or an Armoured Car in Madrid I doubt I would have been able to capture it this turn, so there was an element of luck too.
I agree with improving the defence of cities, it is something I overlooked. Why are cities the bonus from city walls compared with stackable terrain? I'm guessing stackable (if fortress) is double defence, but the Civiliopedia says city walls are triple defence. Is this incorrect, or am I missing something?
I totally agree with the removal of the Sun Tzu wonder, it is too big of an advantage and it makes it less fun for the Nationalist player too. I like it when one of my units gains veteran status and has to be nursed back to health for a future mission.
The number of event generated units was something I gave a lot of thought to. The numbers I used were the most historically accurate I could get. However, game play is much more important than accuracy. This is easily remedied by reducing the number of units from each event. At the moment I would say I have a surplus of good units which has allowed me to strike in several places at once. If the numbers were reduced I would have to be a bit more selective and that would give you the chance to react.