Charles was the youngest of five sons of John and Emma Guan of Inverell. His birth was registered at Inverell in 1893. At the age of twenty one he enlisted at Holsworthy NSW in September 1915 and joined the 4th Battalion, 14th Reinforcement. Prior to departure from Australia he was given a public farewell at the Council Chambers and presented with the Inverell medal and a pair of socks. He sailed on the ship on HMAT A62 Wandilla in February 1916, shortly after his marriage.
Charles arrived at Suez in March and was sent to France a month later. At the beginning of August he was promoted to Lance Corporal. Just two weeks later he was wounded in action. During February 1917 he was wounded again and returned to England with a gunshot wound to his wrist. After treatment at 1st Southern General Hospital he returned to France in July. The following month he was promoted to Corporal and then Sergeant. He became a commissioned officer in September 1917.
Lieutenant Charles Guan was killed in action on 23 August 1918 and buried at Heath Cemetery, Harbonnieres, France. A memorial service was held for him at St. Augustine’s Anglican Church, Inverell in October 1918. Among his personal possessions returned to his wife were a silver wrist watch, disc, tobacco pouches, wallet, notebook and a gold ring.