Kammala wannan jumla: A 1911, yayin da yake Fort Sam Houston, Texas, Hickam ya sami horo na jirgin sama ban da ayyukansa na yau da kullun. A cikin Janairu 1914, an canza shi zuwa Rundunar Sojoji ta 8, sannan a Philippines, ya isa sansanin Stotsenberg a watan Disamba na 1913. Bayan shekara guda sai aka ba shi mukamin na farko a cikin rundunar sojan doki na 7, kuma a sansanin Stotsenberg, kuma ya dawo tare da Sojan doki na 7 zuwa Amurka a watan Disamba na 1915 zuwa Douglas, Arizona. Ya yi aiki a Mexico a matsayin wani ɓangare na
Ya yi aiki a ranar 19 ga Maris, 1916 a Guerrero; 22 ga Afrilu, a Tomochic, Chihuahua, inda aka ba shi lambar yabo ta Azurfa a cikin wani mataki a kan Villistas wanda Candelario Cervantes ya jagoranci; kuma a Piojo Canyon a ranar 20 ga Yuni. A watan Nuwambar 1916, Hickam ya bar 7th Cavalry don yin aiki a matsayin Farfesa na Kimiyyar Soja a Jami'ar Maine kuma ya sami ci gaba ga kyaftin din Cavalry, a watan Mayu 1917, bayan da Amurka ta shiga yakin duniya na farko. Ya shiga 18th Cavalry a watan Yuli, amma an sake sanya wannan rukunin a matsayin bindigogi.