Sentence:  bursting from the lips of a charging cavalry <WSD>trooper</WSD> was the last sound heard on this earth by untold numbers of Cheyennes , Sioux and Apaches , Mexican banditos under Pancho Villa , Japanese in the South Pacific , and Chinese and North Korean Communists in Korea . 
Meaning of the word marked with <WSD> tags:  a soldier in a motorized army unit