Dashiell Samuel Hammett was born in St. Mary's County, Maryland. He grew up in Philadelphia and Baltimore. Hammett left school at the age of fourteen and held several kinds of jobs thereafter–messenger boy, newsboy, clerk, operator, and stevedore, finally becoming an operative for Pinkerton's Detective Agency. Sleuthing suited young Hammett, but World War I intervened, interrupting his work and injuring his health. When Sergeant Hammett was discharged from the last of several hospitals, he resumed detective work. He soon turned to writing, and in the late 1920s Hammett became the unquestioned master of detective-story fiction in America.