With the outbreak of First World War, Catcheside served in the British Army where posted to the Royal Field Artillery, reaching the rank of second-lieutenant. He served his country again in the Second World War, once more in the Royal Field Artillery, where he was lieutenant-colonel.
Catcheside's military service was marked by two periods: World War I and World War II, both involving the Royal Field Artillery and his progression through ranks from second-lieutenant to lieutenant-colonel.