The lay-out of the Short 'Stirling', the largest operational bomber in service in 1942, with the royal air force, showing at a glance the many problems in engineering, labour and man-hours involved in its construction. The Stirling was a four engined bomber in use at the start of World War II. It had a relatively short service life as a bomber, from 1941 to 1943 when it was replaced by the Halifax and Lancaster.