Oscar Harmer of Cardiff served with the 'Cardiff City Battalion' (16th Battalion, Welsh Regiment) and then with the King's Shropshire Light Infantry. While with the Cardiff City Battalion, he was the personal runner for the commanding officer, Lt-Col. Frank Gaskell, and he was by Gaskell's side when he was killed by an enemy sniper. Oscar was awarded the Distinguished Conduct Medal while serving with the KSLI in 1918: the citation reads "For most conspicuous gallantry and devotion to duty. In the attack on Fresnoy-le-Petite, 19th September, 1918, when all the officers of his company had become casualties, he reorganised the company and took command. Later, with half a platoon and one Lewis gun, he captured an enemy post, from which he silenced a hostile machine-gun with Lewis gun fire, and succeeded in keeping down the fire of enemy snipers. The post was repeatedly attacked by the enemy with bombs and rifle grenades, but chiefly due to his fine example and energy all attacks were repulsed, though nearly all his men were wounded. Eventually he successfully withdrew his men under cover of darkness".