Cicely Hamilton was born Cicely Hammill in London, the daughter of Danzil Hammill, a British army officer, and Maude Piers. When Cicely was 10 years old, her mother disappeared from her life. Although Cicely always refused to talk about it, it is believed that her mother was committed to a psychiatric institution. While her father was serving abroad, Cicely was brought up by foster parents. She first worked as a teacher, but wanted to go on the stage. She got a job as an actress with a touring company and changed her name to Hamilton. When she could not get leading roles in London, Cicely Hamilton turned to writing plays, novels, and nonfiction. One of her first plays, Diana of Dobsons, was an immediate success. In 1908, she joined the Women's Social and Political Union, but after a few months left to join the breakaway Women's Freedom League. She also became a co-founder with Bessie Hatton of the Women Writers' Suffrage League. At the outbreak of World War I, she became one of the first to join the new Scottish Women's Hospitals Committee and helped establish a hospital at Royaumont Abbey in France. During the summer of 1916, she nursed soldiers wounded at the Battle of the Somme. In 1917, she left the organization and soon afterwards was asked to form a repertory company at the Somme. For the rest of the war, the company performed for Allied soldiers fighting on the Western Front. After the war, Cicely Hamilton became a freelance journalist, writing for newspapers such as the Daily Mail, the Daily Mirror and the Daily Express, and as a playwright for the Birmingham Repertory Company. She also was a regular contributor to the feminist journal Time and Tide. Her war novel William: An Englishman was awarded the Prix Femina Vie Heureuse-Anglais in 1920. Her autobiography, entitled Life Errant, was published in 1935.