[MLD-Grounds-Keeper-Willie]

I think that first Saruman would have had his army, or what was left of it, take care of the problems of the ents at Isenguard. I don't have my book with me at the moment so correct me if I'm wrong, but by the time his army would get back, Isengaurd would be in ruins (the part that Saruman built to spawn orcs and any other addons). So, he couldn't start repairing his army and he couldn't try rebuiling his machines- it would take too long.

With that said, I think he would do one of two things. He might have felt cocky and decided to take on Sauron, or he would think strategically and keep his alliance with Sauron and attack Minas Tirith.

But it depends on how big his army is. If it was too small, he probably would not want to go against Sauron. The free peoples would not likely trust him. His best choice would probably be to wage war against Minas Tirith with Sauron. After all, he wanted the ring, and Saruman probably assumes it's at Minas Tirith, or will be at least.

But if his army is strong enough, he might go against Sauron. How? I don't know really, but it would be either directly, or with Minas Tirith. And he would probably have to attack Mordor's forces without an official alliance from Minas Tirith. Denethor would not trust Saruman after he destroyed Rohan and especially if he knew that it was Saruman's forces who killed Boromir. So, by attacking Mordor's forces, like that, it might work out since they are proving that they are at least against Sauron.

I could carry this on for a long time, but I'm getting confused, so that's it.