After the battle was over Keysor was evacuated from Gallipoli suffering enteric fever. He eventually rejoined the 1st Battalion after they had been transferred to France in early 1916. In March 1916 Keysor took part in the Battle of Pozières. In November 1916 he was transferred to the 42nd Battalion and promoted to the rank of sergeant on 1 December. On 13 January 1917 he was commissioned and promoted to the rank of second lieutenant. Six months later he was promoted to lieutenant. On 28 March 1918 Keysor was wounded and was evacuated from the line before returning to take part in the fighting at Villers-Bretonneux, where he was gassed on 26 May 1918.