[174] When Wilson asked Congress to declare war on Germany in April 1917, Taft was an enthusiastic supporter; he was chairman of the American Red Cross' executive committee, which occupied much of the former president's time.[175] In August 1917, Wilson conferred military titles on executives of the Red Cross as a way to provide them with additional authority to use in carrying out their wartime responsibilities, and Taft was appointed a major general.[176]
During the war, Taft took leave from Yale in order to serve as co-chairman of the National War Labor Board, tasked with assuring good relations between industry owners and their workers.[177] In February 1918, the new RNC chairman, Will H. Hays, approached Taft seeking his reconciliation with Roosevelt. While at the Palmer House in Chicago, Taft heard that Roosevelt was there having dinner, and after he walked in, the two men embraced to the applause of the room, but the relationship did not progress; Roosevelt died in January 1919.[178] Taft later wrote, "Had he died in a hostile state of mind toward me, I would have mourned the fact all my life. I loved him always and cherish his memory.