In June 1917 Juan registered his Selective Service Card with the local draft board in Wichita Falls, Texas. Six months later he was drafted. He joined the 6th Co. 1st Infantry Training Regiment on December 11, 1917. He boarded the troopship SS Tuscania in January 1918, bound for Le Havre, France. The Tuscania was torpedoed by a German U-boat February 5, 1918 in the North Channel (U.K.), and 200 American Troops perished along with an additional 65 crew members of the Tuscania. Juan was rescued and taken to Ireland, and eventually made his way to the location of his regiment's encampment.