John Stanley Bannon was born at Dublin on 18 December 1893, the eldest son of James and Ellen Bannon. He was educated at Christian Brothers School Dublin before working as a land agents clerk. He migrated to Australia in 1914, where he worked various jobs including agricultural work, clerical work. He was working as a waiter when he and his brother Nicholas enlisted in the Australian Imperial Force on 10 March 1916 at Brisbane.
Bannon embarked from Sydney on 30 September 1916 aboard HMAS Aeneas. He disembarked at Plymouth on 19 November 1916. Bannon proceeded to France in March 1917.
Bannon spent time in hospital in England after being gassed at Belgium towards the end of October 1917. In his letters to his father, he describes being gassed and the effect this has on him and his brother Nicholas. He re-joined his unit during June 1918.
Bannon died instantly on 7 August 1918 after an iron splinter pierced his heart while he was trying to extinguish a fire in a tank. John Stanley Bannon was 24 years old and is buried at Longueau British Cemetery, France.