Cecil was the eldest child of Charles and Harriett Willis. His birth was registered at Inverell in 1897. As an eighteen year old Labourer of Tingha NSW, he enlisted at Inverell in December 1915 and agreed to serve from 12 January 1916. On that day he joined the men known as the First Contingent of The Kurrajongs who left Inverell together for camp.
He became a member of the 33rd Battalion, C Company which trained at Armidale and Rutherford prior to sailing from Australia in May 1916. After nine weeks at sea, the Battalion arrived in England where further training took place at Salisbury Plain. In September Cecil was transferred to the 3rd Battalion and sent to France. By January 1917 he was ill and sent back to England where he was admitted to London General Hospital for treatment of tuberculosis. Three months later he was transferred to the 63rd Battalion. In September he attended Brigade Signal School and then transferred back to the 3rd Battalion. In March 1918 Cecil was sent to France to rejoin his unit there.
He returned to Australia and was medically discharged in 1919. In 1924 he was living at Hamilton, Newcastle NSW.
Private Willis has his name inscribed on the Inverell Honor Roll.