He published it as a book in 2013. It's stunning in its black and white detail. Sacco notes in the video below how the loss of life struck him. In the first hour of the battle, 10,000 British soldiers were killed.
His 24 panels outline the moment the soldiers went over the top and started to get cut down.
I may order the book and unfold the panels in the hallway outside of class and have the students make observations about each panel.