 Nyora kupfuurira kweiyi ndima - Muna March 1918, Harmon akaenda kuFrance neF Troop, 2nd Cavalry. 2nd Cavalry ndiyo chete Cavalry unit yakaenda mhiri kwemakungwa munguva yeHondo Yenyika I, uye B, D, F, uye H Mauto vakava vekupedzisira vakatasva mabhiza eU.S. Cavalry mauniti kuti vambobatana nemuvengi muhondo. Harmon akashanda muBaccarat Sector, paCamp du Valdahon, St. Mihiel Offensive, uye Kurwisa kweMeuse-Argonne. Akashanda muFrance neBelgium pashure pehondo, uye akadzokera kuU.S. muna June 1919 kuti ave mudzidzi paFort Riley, Kansas Cavalry School. 