Defending Rohan during the battle of the Pennor Fields

[Galadriel55]

Originally Posted by tom the eldest

Communication is probably not a problem,because the rider of rohan is very fast,and the could possibly outrun sauron's warg and use different path from sauron'armies.and rohan may holed up in hornburg,flee to dunharrow,or go straight to isengard where the ent will protect them.

If the city is beseiged, you have to get around the enemy troops. Even if there's no siege, but just orcs all over the surrounding land (at a distance), it's nearly impossible for a rider to get through. He could outride one orc on a warg, or even one group of orcs, but he can't ride through an army. The goal is not only to get out of one city, but also into another, and they are very far away. Lots of orc camps to pass on the way. Speed or no, it's like playing tag with everyone around you being "it".