I would say that it would be best to have a realtime combat system where you can't control dwarves personally. After all, your dwarf commanders know what they're doing! (Even if they don't.) Who is the player to tell them how to wage war? Surely not some omnipresent, omniscient entity with the ability to review the whole map at once! Besides, the player
watches the dwarves sleep. If that's not creepy, I don't know what is.
I would definitely recommend allowing you to actually monitor the battles, of course (a time-capsule doesn't break much fiction), and showing full battle spam in any given "outside-the-fortress" battlefield so you can pay attention to how your troops are doing, but I would still have to say you should have a mostly hands-off policy on troops in the field -- these dwarves don't have radios, and besides if you had manual control you'd be far superior to the AI, meaning you could probably wipe out a whole fort with far inferior numbers.
A big portion of strategic fighting would likely involve alliance with other dwarf clans, to be capable of getting the numbers necessary to perform assaults on foreign territory.
The diplomat says, "Then it is agreed!
The Dwarven Halls of Grukgruk will provide 100 soldiers, consisting of 30 axedwarves, 40 sworddwarves, 10 marksdwarves, 15 pikedwarves, and 5 speardwarves.
However, Her Regency insists that we shall not bring all troops if you do not also commit at least the same number yourself."