Complex sentence: The 25th Infantry was one of the racially segregated units of the United States Army known as Buffalo Soldiers, which often sought out Civil War veterans from colored regiments such as the 5th USCC.
Split into simpler sentences: The 25th Infantry was one of the racially segregated units of the United States Army known as Buffalo Soldiers. These units often sought out Civil War veterans from colored regiments such as the 5th USCC.