The Bell 205 is the further development of the Bell 204, which was in service with the US armed forces from the mid-1950s. The first flight of the new model took place on August 16, 1961, and deliveries to the military began in 1963 under the designation UH-1D. Over 12,000 units (both civil and military) were built up until the 1980s, including by licensees in other countries. Many of the helicopters remain in service.