Complex sentence: He has served or commanded at every level, and he has been assigned to all of the Combat Training Center in the United States and Germany; he has influenced the training model in the U.S. Army at various stages of his career.
Split into simpler sentences: He has served or commanded at every level, and he has been assigned to all of the Combat Training Centers in the United States and Germany. Hertling has influenced the training model in the U.S. Army at various stages of his career.