Brooks served on the Western Front in the Champagne-Marne Defense, the Aisne-Marne Offensive, the St. Mihiel Offensive and the Meuse-Argonne Offensive. On October 5, 1918, during the Meuse-Argonne Offensive, he earned a Distinguished Service Cross "for extraordinary heroism in action" at Montfaucon, France when he "... exposed himself to heavy and accurate artillery fire directed on an ammunition train while driving a loaded ammunition truck to safety, the driver of which had been killed by enemy fire."