Kammala wannan jumla: A ranar 17 ga Maris, 1917, an tura Dakarun Sojoji na 3 zuwa Fort Sam Houston, Texas, kuma wata daya bayan haka, Amurka ta shiga yakin duniya na farko a bangaren Allies. Rundunar ta kasance ɗaya daga cikin rukunin farko da suka isa Faransa a watan Nuwamba na wannan shekarar, kuma nan da nan suka fara aikinsu; aiki na manyan wuraren ajiyar doki uku. An caje ƙungiyoyi uku tare da sayen dawakai, mules da fodder, kulawa, yanayin, da kuma horar da remounts kafin a bayar, da kuma rarraba da kuma bayar da remounts ga Amurka Expeditionary Force. The kawai 3rd Cavalry naúrar ganin aiki a yakin duniya na I ya K Sojoji, ware daga 3rd rundujar soja masu dawaki, da Sojoji bauta a I Corps a lokacin Aisne-Marne Offensive (18 Yuli <unk> 6 Agusta 1918), da kuma a III Corps a kan
Vesle Front (7-17 Agusta), Oise-Aisne Offensive (18 Agusta <unk> 9 Satumba), da kuma Meuse-Argonne Offensive (14 Satumba <unk> 11 Nuwamba).