Complex sentence: He was born in Galena, Illinois, in a Polish-American family (origin family's name was Schwałka, as he once signed), and graduated from the United States Military Academy at West Point in 1871.
Split into simpler sentences: He was born in Galena, Illinois, in a Polish-American family whose ancestors spelled the name Schwałka, as he once signed. He graduated from the United States Military Academy at West Point in 1871.