Rocket artillery is artillery that uses rockets as the projectile. The use of rocket artillery dates back to medieval China where devices such as fire arrows were used (albeit mostly as a psychological weapon). Fire arrows were also used in multiple launch systems and transported via carts. The first true rocket artillery was developed in South Asia by Tipu Sultan, the ruler of the Kingdom of Mysore. In the late nineteenth century, due to improvements in the power and range of conventional artillery, the use of early military rockets declined; they were finally used on a small scale by both sides during the American Civil War. Modern rocket artillery was first employed during World War II, in the form of the German Nebelwerfer family of rocket ordnance designs, Soviet Katyusha-series and numerous other systems employed on a smaller scale by the Western allies and Japan. In modern use, the rockets are often guided by an internal guiding system or GPS in order to maintain accuracy.