John Frederick Bagot was born on 13 February 1886 in Grange, South Australia. At the time of enlisting in the First World War he was 28 years old and a farmer. Bagot enlisted during September 1914, initially training with the 9th Light Horse at the Morphettville camp, before transferring to the 13th Light Horse at Broadmeadows. Bagot married Eileen "Billie" Dubois Ive, the week before he embarked. He embarked on 28 May 1915, holding the rank of second lieutenant. He arrived on Gallipoli in September, serving there for four months. From July 1916 he was on the Western Front. Bagot was promoted to the rank of captain in November 1917. He received a Mentioned in Despatches certificate, dated 7th April 1918, "for gallant and distinguished services in the Field". Bagot returned to Australia in February 1919, and discharged on 18 May 1919.