World War I
When war was declared the Staff of the Irish Command became automatically the staff of the II Army Corps and accordingly with the outbreak of World War I in August 1914, he was promoted to the temporary rank of brigadier general, and as part of the British Expeditionary Force (BEF) in France took charge of the adjutant and quartermaster-general's department during the retreat of the II Corps after the Battle of Mons, to Paris, and during the Battle of the Marne. In the middle of September 1914, he relieved one of the brigadiers in the fighting line, Gerald Cuthbert, as commander of the 13th Infantry Brigade, part of the 5th Division. He was in command until 14 January 1915 when he relinquished his brigade and temporary rank, reverting to colonel, and being placed on half-pay although this date was later amended to 24 February.
He then commanded the 53rd Infantry Brigade of the 18th (Eastern) Division until December 1915, when he was ordered home to assume command of the 16th (Irish) Division at Blackburn.
Promoted to the temporary rank of major general that same month, Hickie took over from the much older Lieutenant General Sir Lawrence Parsons. Hickie – one of a rare breed, a senior, Irish, Catholic officer – was a popular replacement. It was politically a highly sensitive appointment which required the professionalism and political awareness Hickie, fortunately, possessed as the division was formed around a core of Irish National Volunteers in response to Sir Edward Carson's Ulster Volunteers. He was much more diplomatic and tactful than his predecessors and spoke of the pride which his new command gave him, but did not hesitate to make sweeping changes amongst the senior officers of the 16th Division. After putting the division through intensive training, it left under Irish command, of which each man took personal pride. It arrived in France in December 1915.
In the next two years and four months during which Hickie, who in January 1917 was promoted to the permanent rank of major general, commanded the 16th (Irish) Division, it earned a reputation for aggression and élan and won many memorials and mentions for bravery in the engagements during the 1916 Battle of Guillemont and the capture of Ginchy (both of which formed part of the Battle of the Somme), then during the Battle of Messines, in appalling conditions the Battle of Passchendaele and in attacks near Bullecourt in the Battle of Cambrai offensive in November 1917.
During this period the division made considerable progress in developing its operational techniques but at a price in losses. The growing shortage of Irish replacement recruits (due to nationalist disenchantment with the war and the absence of conscription in Ireland) was successfully met by Hickie by integrating non-Irish soldiers into the division.
In February 1918, Hickie was invalided home on temporary sick leave, but when in the hospital the German spring offensive began on 21 March, with the result that after his division moved under the command of Lieutenant General Hubert Gough, commander of the British Fifth Army, it was practically wiped out and ceased to exist as a division. Although promised a new command, this did not happen before the war finally ended due to the armistice with Germany in November. Hickie had typified the army's better divisional commanders, was articulate, intelligent and had been competent and resourceful during the BEF's difficult period 1916–1917, laying the foundations for its full tactical success in 1918. He was advanced to Knight Commander of the Order of the Bath in January 1918, and awarded the Croix de Guerre in December 1919.
