Jack joined the Denbighshire Hussars, a yeomanry reserve regiment on 20th February 1914 and remained in the UK until 2nd March 1916.
He arrived in Alexandria, Egypt on 15th March 1916 having sailed from Devonport on the HMT Haverford twelve days earlier. On 23rd June 1916 Jack was deprived of ten days’ pay for breaking censorship rules in his private correspondence. On 16th December 1916, he was transferred to the 24th Battalion of the Royal Welsh Fusiliers, the regiment which absorbed the rest of the Denbighshire Hussars later on.
He stayed in a place which is more famously associated with the Second World War – El Alamein, where he was promoted, and spent ten days in hospital at Sherika in January 1917, suffering from diarrhoea.
On 6th December 1917 he died from wounds received whilst fighting in Palestine, presumably at the Battle of Beersheba on 31st October, when British, Australian and New Zealand soldiers defeated the Turks.