By 1911 he was a major with the South Wales Borderers 2nd Battalion and stationed at Pretoria in South Africa. He was appointed to raise and command the new 4th Service Battalion of the Borderers in 1914. Colonel Gillespie was killed by a sniper while directing the fire of a machine gun in defence of Damakjelik Bair (later named Gillespie Hill).
He left a widow and three children, Rollo, Henry and Phillis, born respectively 1910, 1913 and 1915.
Extract from the Brecon and Radnor Express 13th January 1916:
‘Traditions Well Maintained by new army in Gallipoli’
HIGH TRIBUTE TO LATE COLONEL GILLESPIE.
‘In the tragic story of Suvla Bay, told in the report of Sir Ian Hamilton, another glorious page is added to the annals of the 24th S.W. Borderers. There were 14 or 15 Welsh units engaged, and to some of these, notably to the part played the Left Covering Column the 4th South Wales Borderers, in the night attack on Sari Bair Ridge, Sir Ian Hamilton refers at length, and pays a high tribute to. Lieut. Col. Gillespie.
The left covering column, under Brigadier General Travers, after marching along the beach to No. 3 Outpost, resumed its northerly advance as soon as the attack on Bauchop's Hill had developed. Once the Chailak Dere was cleared the column moved by the mouth of the Aghyl Dere, disregarding the enfilade fire from sections of Bauchop's Hill still uncaptured. The rapid success of this movement was largely due to Lieutenant Colonel Gillespie, a very fine man, who commanded the advance guard consisting of his own regiment, the 4th South Wales Borderers, a Corps worthy of such a leader.
Every trench encountered was instantly rushed by the Borderers until, having reached the predetermined spot, the whole column was unhesitatingly launched at Damakjelik Bair. Several Turkish trenches were captured at the bayonet's point, and by 1.30 a.m. The whole of the hill was occupied, thus safe guarding the left rear of the whole of the Anzac attack. Here was an encouraging example of what the New Army, under good auspices, could accomplish. Sad to say, the Borderers lost their intrepid leader, Lieutenant Colonel Gillespie, in the course of this affair.
He was an old campaigner who commanded at the Depot, Brecon before the War. He received his first commission in the South Wales Borderers in 1890 and in 1890 was promoted Captain and Major in 1909. He also took part in the 1897-98 West African operations and also fought in South Africa’.