Shot in the chest he was evacuated to hospital where it was realised that the bullet had entered the chest pocket of his uniform, travelled into the cigarette case he kept there and was stopped by the case before reaching his vital organs.
Gibson had the cigarette case to thank for saving his life. Remarkably he had the presence of mind to ensure that both the case and the pocket from his uniform were kept as a souvenir of his lucky escape.
He sent the case and pocket to Abdulla & Co., the manufacturers of the cigarettes, who replied on 10 January 1917 asking if they could keep the case and enclosing a parcel of cigarettes to be shared amongst his friends. William refused them permission to keep the souvenir and it was duly returned to his mother in Dublin that April.
William Gibson survived the war and returned home. Living in a house of the Irish Sailors' and Soldiers' Land Trust in Killester he worked as a postman. Until his death in March 1962 he carefully kept the case as a reminder of his experience of the war. He is buried in AL 69 St. Patrick’s.