Pratt's long and active military career included eight years in the Great Plains, during the Indian Wars. He participated in the Washita campaign of 1868–1869 and the Red River War of 1874–1875. The severe winter of 1874-1875 resulted in many hostiles surrendering to US Indian Agents for their tribes. Pratt was responsible for gathering testimony to assess charges against men for actions outside warfare. He worked with interpreters and prisoners to clear as many charges as possible.