On 4 June 1915, Corkhill enrolled as a staff nurse in the Australian Imperial Force. She left Fremantle aboard the A62 "Wandila" on 25 June 1915, and arrived in Egypt in July that year. She was assigned to the 1st Australian General Hospital, and assisted in the treatment of soldiers involved with the Gallipoli Campaign. On 24 March 1916, Corkhill was among a group of nurses sent to Marseille aboard the "Braemar Castle", a hospital ship. Arriving in early April, she was then sent aboard a train destined for the 2nd British General Hospital in Le Havre. The train was poorly equipped and was missing many amenities, such as toilets or water, so the women were forced to improvise by washing with cologne. In her time at the British hospital, Corkhill looked forward to returning to an Australian hospital and being "amongst our boys"; the Australian soldiers often found their compatriots to be friendlier than the British nurses. On Anzac Day 1916, a year after the landing at Gallipoli, Corkhill and two other Australian nurses commemorated the occasion. They wore gum tree leaves on their capes, and gave small packets of cigarettes and matches to the Australians who were interned at the hospital as gifts.