Cyril Gain was born in 1895 and was the eldest child of Frederick Gain and his wife, Martha, nee Bartholomew. In the years that followed the family grew, until there were eleven young Gains, 5 boys and 6 girls. His younger brother, Augustus, was also to join up for the war and be invalided out. Cyril Gain was a country boy, born in Tumbarumba, NSW, and was to remain faithful to the Wagga Wagga district, where he grew up, for most of his working life. In late 1915, when he enlisted, he was nearly twenty-one years old, working as a clerk and living at 72 Gipps St., East Melbourne. Later, he would give his address as 'Kamarooka',  138 Powlett St., East Melbourne (known locally as the Opera House because of its unusual balcony) and, on 26 July,1919, would marry his first wife, Marjorie Wanda Samson, at  St Peter's, Eastern Hill. She died in 1925 and this seems to have precipitated a permanent move away from Melbourne.

Cyril Gain moved into training on 4 January, 1916 and trained util 31 March as a Gunner. He was attached to Field Artillery Brigade 8, Battery 29 and on 20 May, 1916, embarked on HMAT Medic A7 for England and then, the Western Front. He was sent to France on 30 December, 1916, and two months later accidentlly damaged his ankle. This did not seem to take him away from the front, but on 22 July, he as caught absent from his billet without a pass and suffered the relatively hard punishment of nine days Field Punishment, plus a fine. The real damage was done on 26 September that year, when he was caught in a German gas attack and became severely ill. He was sent back to England from Rouen and placed in the Temporary Hospital at Exeter, before being transferred on 1 November to the 3rd Auxiliary Hospital, presumably for convalescence. On 5 November, he was discharged from hospital and sent to Weymouth, his record still saying he had gas poisoning.

He was again in hospital on 11 July, 1917, before rejoining the 8th Field Battery at the front on 18 July, but was again sick on 8 August, all seemingly connected with the effects of the gas attack.  He was back at the front again on 19 August, but was wounded in action on 24 September. On 13 October, 1917, he was invalided back to England and put in hospital at Exeter the next day, again with gas poisoning. This marked the end of his military career. He was sent home on 10 Januaryy, 1918. on HT Corinthic for discharge from the AIF, the reason given, again, was gas poisoning. On 4 April, 1918, back in Melbourne, he was released from further service.

Following Marjorie's death, he married again in 1926,, to Elva Beatrice Reid and then in 1944, to Heather Jean Ashwin. By 1943, he was an accountant living at 45 Scarborough St., Kogarah, south of Sydney, and stayed there until 1949, when they moved to 61 Mutch St., Kyeemagh. Cyril Gain died at Petersham NSW on 11/2/1956.