Osgiliath and Minas Tirith

[Amroth]

In the Two Towers and Return of the King, it becomes evident that Sauron's armies must take Osgiliath before they try to take Minas Tirith. Why is this? Is there some military strategy that I'm missing? Why can't Sauron's armies just go around Osgiliath before taking Minas Tirith?

Thanks. :)

[Laurelin]

Hmm...not sure. I'd have to pulls some of my books out and do some research. I'll get back to you on this one. ;)

[JeffF.]

The strategic importance of Osgiliath was because it was a crossing point. Though bridges had been destroyed they could be repaired and also the eastern half of the city could be used as a staging area for the assault across the river (Sauron's troops would be hidden from view from Gondor troops). Cair Andros was the other potential crossing point for armies. Individuals could with some difficulty crosss almost anywhere but troops and equipment and beasts needed to go through one of the two. Farther upstream there were comse crossings (referred to in Unfinished Tales) in the area of Rohan.