During the Spanish–American War and Philippine Insurrection, Gibbs served in the volunteer forces, mainly on Signal Corps duty, in ranks from private to first lieutenant.

[4] During World War I, Gibbs was the assistant Chief Signal Officer of the American Expeditionary Forces.

[2] Gibbs was awarded the Distinguished Service Medal for his participation in the Aisne-Marne and Meuse-Argonne offensives.

The citation for the medal reads: The President of the United States of America, authorized by Act of Congress, July 9, 1918, takes pleasure in presenting the Army Distinguished Service Medal to Brigadier General George S. Gibbs, United States Army, for exceptionally meritorious and distinguished services to the Government of the United States, in a duty of great responsibility during World War I.

[1] His son David Parker Gibbs was a career army officer who attained the rank of major general and also served as head of the signal corps.