During World War I, Burnham was selected as an officer and recruited volunteers for a U.S. Army division similar to the Rough Riders, which Theodore Roosevelt intended to lead into France. For political reasons, the unit was disbanded without seeing action. After the war, Burnham and his business partner John Hays Hammond formed the Burnham Exploration Company; they became wealthy from oil discovered in California. Burnham joined several new wilderness conservation organizations, including the California State Parks Commission. In the 1930s, he worked with the BSA to save the big horn sheep from extinction. This effort led to the creation of the Kofa and Cabeza Prieta National Wildlife Refuges in Arizona. He earned the BSA's highest honor, the Silver Buffalo Award, in 1936, and remained active in the organization at both the regional and national level until his death in 1947. To symbolise the friendship between Burnham and Baden-Powell, the mountain beside Mount Baden-Powell in California was formally named Mount Burnham in 1951.