Disappearing gun A disappearing gun ( often called a disappearing carriage ) was a type of heavy ( mainly coastal ) artillery used in the past for which the gun carriage enabled the gun to rotate backwards and down into a pit protected by a wall ( the parapet ) or a bunker after it was fired . This retraction lowered the gun from view by the enemy while it was being reloaded . It also made reloading easier , since it lowered the breech to a level just above the loading platform , and shells could be rolled right up to the open breech for loading and ramming . Although it had these advantages , the disappearing carriage was also a complicated mechanism . In the U . S . , disappearing carriages were mostly withdrawn from active service by the early 1920s . The disappearing gun was usually moved down behind the parapet or into its protective housing by the force of its own recoil , which ( on many models ) lifted a counterweight . Before firing , the crew tripped a catch on the counterweight , causing it to fall into a well at the center of the gun position and move the gun back up " into battery " ( firing position ) . Some disappearing guns also used compressed air , while a few were built to be raised by steam . Advantages . The disappearing carriage had several principal advantages : Disadvantages . The disappearing gun had several drawbacks as well : History . Disappearing guns as a functioning concept were invented in the 1860s by Captain ( later Sir ) Alexander Moncrieff , who built on his observations in the Crimean War to improve on existing designs for a gun carriage capable of rising over a parapet before being reloaded from behind cover . His key innovation was a counterweight system that raised the gun as well as controlled the recoil . Moncrieff promoted his system as an inexpensive and quickly constructed alternative to a more traditional gun emplacement . Buffington and Crozier further refined the concept in the late 1880s by incorporating hydro - pneumatic recoil control to assist the counterweight action . The Buffington – Crozier Disappearing Carriage ( 1893 ) represented the zenith of disappearing gun carriages , and guns of up to 16 - inch size were eventually mounted on such carriages . Disappearing guns were highly popular for a while in the British Empire , the United States and other countries . However , in the 1890s , a series of Royal Navy / New Zealand Division of the Royal Navy trials carried out in New Zealand ( where numerous disappearing guns had been bought and installed during the Russian Scares ) , revealed the virtual impossibility of a small shore installation being hit by a warship , except by chance . Others dispute that the advantages were so limited , and point to the efficiency of such artillery in for example , the Battle of Port Arthur . In any case , with their protective benefits thus cast into doubt , no further production of the expensive gun carriages was undertaken in New Zealand . Though effective against ships , the guns turned out to be vulnerable to aerial attack . After World War I batteries of disappearing guns were usually casemate d for protection or covered with camouflage for concealment . By 1912 , the guns were declared obsolete in the British Army , with only some other countries , particularly the United States , still producing them up to World War I and keeping them active through to the end of World War II . Other applications . Gun lift battery . One unique and even more complex type of disappearing gun was Battery Potter at Fort Hancock , Sandy Hook , New Jersey . Built in 1892 , the Battery covered the approaches to New York harbor . Instead of using recoil from the gun to lower the weapon , two 12 - inch barbette carriages were placed on individual hydraulic elevators that would raise the 110 - ton carriage and gun 14 feet to enable it fire over a parapet wall . After firing , the gun was lowered for reloading using hydraulic ramrods and a shell hoist . While the operation of the battery was slow , taking 3 minutes per shot , its design allowed an unlimited field of fire . Battery Potter required a huge amount of machinery to operate the gun lifts , including boilers , steam pressure pumps and two accumulators . Due to the inability to generate steam quickly , Potter ' s boilers were run nonstop during its 14 - year life , creating a significant operating cost . After the proving of the Buffington Crozier carriage , the United States Army abandoned plans to build several additional gun lift batteries . Naval artillery . At least once , the concept was also attempted for conversion to a naval use . HMS " Temeraire " was completed in 1877 with two disappearing gun turrets sinking down into barbette - structures ( basically circular metal protective walls over which the gun fired when elevated ) . This was to combine the ability of the early pivot gun s to swivel with the protection of more classical fixed naval guns . However , the design was not successful and apparently never repeated . It is thought that both harsh saltwater environment and the constant swaying and rolling of a ship at sea were to blame for problems with the complex mechanism .