The high point of the New Zealand effort at Gallipoli was the capture of Chunuk Bair. Two columns of the New Zealand Infantry Brigade carried out the attack, which began on 6 August. The operation started well, but delays meant not all the infantrymen had reached Rhododendron Spur by the time the assault on the summit started next morning. After the Auckland Battalion tried and failed, OIC Lieutenant-Colonel William Malone insisted that the Wellingtons’ attack on the summit should be delayed until after nightfall.

The Wellington Battalion occupied the summit before dawn on 8 August. With sunrise came a barrage of fire from Ottoman Turks holding higher ground to the north. A desperate struggle to hold Chunuk Bair ensued. By the time the Wellingtons were relieved that evening, only 70 of the battalion’s 760 men were still standing. Thomas was one of the casualties along with Lt-Col Malone who was killed by an Allied shell at about 5 p.m.

Ottoman forces recaptured the position on 10 August from British troops who had relieved the New Zealanders.