As early as 1916, after the visit to the school by General Leonard Wood, who had been preaching preparedness throughout the nation, boy volunteers began drilling and playing war games all over the grounds. After the United States entered WWI, an SPS Cadet Corps was formed. Here cadets are seen digging trenches at the Lower Grounds. Forty-eight SPS alumni died in First World War, 762 served in the armies or navies of the United States or of its allies, 192 were engaged in auxiliary war service, and 15 masters left the school to participate in war service.