Commissioned a second lieutenant on 9 January 1904, Quinan joined the Indian Army (27th Punjabis) on 25 March 1905. He was promoted to lieutenant on 9 April of the following year. Before the First World War, he saw active service on the North West Frontier of the British Indian Empire and was promoted to captain on 9 January 1913. During the war he fought in France and Mesopotamia, and was appointed a provost marshal on 7 March 1915. He served at the battles of Neuve Chapelle, Loos and the attempt to relieve Kut al Amara; he was wounded at Beit Aisa. Appointed a GSO 3rd Grade on 10 May 1917, he was brevetted to major on 1 January 1918 and promoted to acting major on 2 November.