Hey everyone, longtime lurker, first time poster.
Following a piece of advice I found on this forum, I've both blitzed The Hornburg with my initial army around turn 8-10 (captured it, massacred the population, burned all the buildings, and left a unit of Snagas to garrison), or called an Invasion on it on Turn 2. Either way, I'm drowning in half stacks of Rohirrim by turn 20.
In my most recent attempt, I called an Invasion (on the Hornburg) at turn 2, then took Tharbad and Talsir to boost my economy. Then I sat back for 10-15 turns and built up economic infrastructure, and focused on Wargs and Ballistas at Isengard, rather than Uruks. A full Invasion Stack from Harad killed off the Hornburg around turn 22, but by that time my armies were whittled down to a nub and I was 4.5k in the red with three more half stacks incoming. I quit at this point.
So how do you get Isengard off the ground?