Like several other early war figures such as Carl Schurz, Thomas F. Meagher, and Michael Corcoran, Sigel was most important in encouraging recent immigrants to enlist in the war effort. As I've said here before his best battlefield performance seems to have been at Pea Ridge/Elkhorn Tavern, Arkansas where he was able to put his specialized training as an artillery officer to good use, overwhelming his Confederate opponents with the fire of massed batteries. But his fellow German soldiers loved him, and I fights mit Sigel was their battle cry.