Complex sentence: The 6th US Infantry and 1st Rifle Regiments made up the military portion of the expedition which arrived at the Council Bluff site on September 19, located near Fort Lisa and Cabanne's Trading Post, private fur trading establishments.
Split into simpler sentences: The 6th US Infantry and 1st Rifle Regiments made up the military portion of the expedition, which arrived at the Council Bluff site on September 19. It was located near Fort Lisa and Cabanne's Trading Post, private fur trading establishments.