Rubuta ci gaba ga wannan sakin layi - A watan Agusta 1917, an ba Gatley mukamin brigadier janar a matsayin kwamandan Brigade na 55 na Field Artillery, wani sashi na 30th Division. Daga bisani an canza shi zuwa umurnin Brigade na 67 na Artillery Brigade na 42nd Division, wanda ya jagoranci har zuwa karshen yakin. Ya shiga cikin Champagne-Marne
, Aisne-Marne, St. Mihiel, da kuma Meuse-Argonne fadace-fadace da hare-hare. Daga Disamba 1917 zuwa Janairu 1918, Gatley ya jagoranci rundunar ta 30. A cikin 1919 ya umurci Rukunin na 42 a lokacin wani ɓangare na aikinsa na bayan yaƙin a Jamus.