Oliver Nugent, Ireland’s longest-serving divisional commander of the Great War, led the Ulster Division on the western front from 1915 to 1918. That period saw the operational transformation of the British army and his own development as a general, from the heroic but doomed assault at Thiepval in July 1916, through the triumph of Messines, the heartbreaking failure at Ypres and the mixed success of Cambrai in 1917, to the great German spring offensive of 1918. Alongside the challenges of divisional command he had to manage the Ulster Division’s political dimension, with its roots in the pre-war Ulster Volunteer Force. The tensions that arose between him and politicians at home over issues like Irish recruitment, relations with the 16th (Irish) Division and, especially, Ulster’s place in a post-war political settlement, reveal not only the conflict between military and political priorities but also the divisions within Irish unionism during the Great War period.More widely, Nugent’s career provides a unique insight into the political decline of the Irish landed class as well as their enduring military tradition — from his financial struggles as a young landlord in the 1880s, his regimental service on India’s north-west frontier and in the Boer war, and his involvement with the UVF in Cavan in 1914, to his role in quelling political unrest in post-war India, his return to an Ireland convulsed by revolution and his adaptation to life in the Irish Free State.