In The Red Badge of Courage, at the start of Chapter 19, what did 304th Regiment do for the first time?

In Chapter Nineteen, the 304th Regiment led the charge for the first time.

He was unaware of the machinery of orders that started the charge, although from the corners of his eyes he saw an officer, who looked like a boy a-horseback, come galloping, waving his hat. Suddenly he felt a straining and heaving among the men. The line fell slowly forward like a toppling wall, and, with a convulsive gasp that was intended for a cheer, the regiment began its journey.