Interesting question Tuor, As Eomer said, a definate alliance between Rohan and Gondor. I do think if Saruman was able to make a great force so fast, Mordor would have allied with Saruman, or would have just stayed out of it and wait for the perfect moment to make it's strike. Here is my true feeling on if Saruman got the ring though...
Saruman if he could figure out a way to wield the ring and get armies to flock to Isengard, then yes, Saruman could overthrow Sauron. Yes, Saruman studied for years in ring-lore, he even tried to make his own ring, which as of right now, it seems that ring was a failure. I'm still not convinced Saruman would know how to do that, his arrogance could get into the way. We have to remember, just because someone has the ring doesn't make them all powerful, unstoppable, first Saruman must know how to use the Ring, for example commanding Sauron's armies, commanding the Nazgul, if Saruman could be able to do that, then we are getting somewhere.
|