rod to break was a factor in their removal. Several mobile disappearing mounts appeared in France and Germany circa 1893. These included both road-mobile and rail-mobile designs. In France, Schneider and St. Chamond produced road-mobile design and rail-mobile designs, in 120 mm (4.7 inch) and 155 mm weapons. The 0.6 meter rail affût-truck system was used tactically for 120mm and 155mm guns in WWI. Six 120 mm Modèle 1882 guns on St. Chamond mounts were deployed at Fort de Dailly in Switzerland from 1894 to 1939. Krupp produced a rail-mobile 120 mm disappearing gun in 1900. Though effective against ships, the guns were vulnerable to aerial observation and attack. After World War I coastal guns were usually casemated for protection or covered with camouflage for concealment. By 1912, disappearing guns were declared obsolete in the British Army, with only a few other countries, particularly the United States, still producing them up to World War I and retaining them in service until replaced by casemated batteries in World War II. The only major campaign in which US disappearing guns played a part was the Japanese invasion of the Philippines, which began shortly after the attack on Pearl Harbor on 7 December 1941 and ended with the surrender of US forces on 6 May 1942. The disappearing guns were the least useful of the coast defense assets, as they were positioned to defend against warships entering Manila Bay and Subic Bay and in most cases could not engage Japanese forces due to limited traverse. Despite attempts at camouflage, their emplacements were vulnerable to air and high-angle artillery attack. Advantages The disappearing carriage had several principal advantages: It afforded the gun crew protection from direct fire by raising the gun over the parapet (or wall in front of the gun) only when it was to be fired, otherwise leaving it at a lower level, where it was also able to be loaded easily. With its guns in a retracted position (down behind the parapet), the battery was much harder to spot from the sea, making it a much harder target for attacking ships. Flat trajectory fire tended simply to fly over the battery, without damaging it. Interposing of a moving fulcrum between the gun and its platform lessened the strain on the latter and allowed it to be of lighter construction while limiting recoil travel. Simple, well protected earthen and masonry gun pits