RPG Vault have posted part one of their Warlords IV: Heroes of Etheria Q&A. In this part Steve Fawkner, creator and designer of the previous titles, talks about Infinite Interactive's new Speed Tactical System and combat in general:
Jonric: What kind of combat system did the previous games use? In what ways did it evolve from Warlords I to II and then III, and what were the main reasons behind this evolution?
Steve Fawkner: Previous games in the Warlords series used a very simple abstract combat system. A group of attackers and defenders were displayed on the screen and then fought (and died) one at a time until only one side remained. There was no user interaction of any kind in the combat - the only way you affected the outcome was to make sure that you had better troops than your opponent going into the fight!
This very simple combat system served us well right up to Warlords III: Darklords Rising. It never really evolved at all, except that the special abilities of the troops grew more diverse and interesting as the series progressed.
We never felt a need to upgrade it back then, for although games like Heroes of Might and Magic and Master of Magic released with tactical combat systems, the Warlords games had always really been about grand strategy, not battlefield tactics. In a sense, you were a King, sending your armies into the field and leaving them in the care of your generals.