A fairly decent photography guide to this brilliant Civil War memorial sculpture can be found here. The expressions on the faces of the men, and of the horses, capture the exertion and agony of battle in a succinct manner one might not expect could be done in bronze.
Here's the wiki that describes what we see.
However, this blogger, Aporetic, in his entry, "The Unseen Spectacular," provides a personal reaction to the sculpture. with both the photographs and the description. It is highly recommended.