21 cm SK " Peter Adalbert " The 21 cm SK " Peter Adalbert " ( SK - Schnelladekanone ( quick - loading cannon ) ) was a German railway gun used during World War I . It served on the Western Front and in Gallipoli between 1916 and 1918 . Eleven were built , using two different surplus naval guns that shared the same mount . Only four are known to have survived destruction after the end of the war . Design . The loss of the armored cruiser during the Battle of Dogger Bank in January 1915 rendered its four reserve " 21 cm SK L / 45 C / 06 " guns surplus as no other ships used them . An order was placed with Krupp to design a " Bettungsschiessgerüst " ( firing platform ) in May 1915 that could use the redundant guns . They were portable mounts that could be emplaced anywhere after several weeks of labor to prepare the position . It rotated on a pivot at the front of the mount and the rear was supported by rollers resting on a semicircular rail and was generally equipped with a gun shield . One obvious change made for land service was the placement of a small counterweight just forward of the trunnions to counteract the preponderance of weight towards the breech . This , although heavy , was simpler than adding equilibrators to perform the same function . The early loss of three out of four armored cruisers of the and classes to mines and submarines made their reserve guns available as well . They used the older " 21 cm SK L / 40 C / 01 " gun of lesser performance , but it could be adapted to use the same mount as the newer guns despite being heavier and with a shorter barrel . s guns also became available when she was disarmed in 1916 . Serial numbers for four " 21 cm SK L / 45 C / 06 " and seven " 21 cm SK L / 40 C / 01 " guns have been identified . The Germans were dissatisfied with the lengthy time required to emplace the " Bettungsschiessgerüst " and , in 1918 , decided to transfer the guns to the " Eisenbahn und Bettungsschiessgerüst " ( " E . u . B . " ) ( railroad and firing platform ) mounts successfully used by other German railroad guns . Only five guns had been transferred to the new mounts before the end of the war . The " E . u . B . " could fire from any suitable section of track after curved wedges were bolted to the track behind each wheel to absorb any residual recoil after the gun cradle recoiled backwards . It also had a pintle built into the underside of the front of the mount . Two large rollers were fitted to the underside of the mount at the rear . Seven cars could carry a portable metal firing platform ( " Bettungslafette " ) that had a central pivot mount and an outer rail . It was assembled with the aid of a derrick or crane , which took between three and five days , and railroad tracks were laid slightly past the firing platform to accommodate the front bogies of the gun . The gun was moved over the firing platform and then lowered into position after the central section of rail was removed . After the gun ' s pintle was bolted to the firing platform ' s pivot mount , the entire carriage was jacked up so that the trucks and their sections of rail could be removed . The carriage was then lowered so that the rear rollers rested on the outer track . Concrete versions were also used . It could have up to 360° of traverse . The " E . u . B . " retained 2° 15 ' of on - mount traverse for fine aiming adjustments . Ammunition on the " E . u . B . " was moved by means of a shot tray provided with two two - man handles , a yoke above with an eye and wheels so that shells could be moved by hand , rolled or carried by the trolley hoist which runs along the overhead rail . An extensible rail could raised and braced in place to reach shells placed on the ground on in an ammunition car behind the mount . The shot tray could be hooked to the breech to hold the powder and shell in place while they were manually rammed . The gun had to be loaded at zero elevation and thus had to be re - aimed after every shot . The " Peter Adalbert " fired several different shells with weights between . It used the German naval system of ammunition , where the base charge was held in a metallic cartridge case and supplemented by another charge in a silk bag which was rammed first . Combat History . The " Peter Adalbert " ' s baptism of fire came on 21 February 1916 in the Battle of Verdun , when a SK L / 45 " in Bettungsschiessgerüst " opened fire at the beginning of the battle . One SK L / 40 " in Bettungsschiessgerüst " was sent to reinforce the defenses of Gallipoli in 1917 and remained there for the rest of the war under the command of " Kommando FR 17 " . Two SK L / 45 and five SK L / 40 guns , all in " Bettungsschiessgerüst " mounts , were produced in 1916 . They were organized into batteries , each with one gun . Known designations were 408 , 428 , 684 , 717 , 746 and 790 . One " Peter Adalbert " " in Bettungsschiessgerüst " participated in the Battle of the Somme in October 1916 . Two " Peter Adalbert " " in Bettungsschiessgerüst " participated in the Battle of Passchendaele in July 1917 and two were stationed opposite Verdun in August 1917 . Seven " Peter Adalbert " guns supported the 1918 Spring Offensive s , although their mount types are not noted . One bombarded the French during the Second Battle of the Marne . One SK L / 45 " in E . u . B . " gun was captured by the Americans in November 1918 and the French captured an SK L / 40 " in Bettungsschiessgerüst " that same month . Only two guns were destroyed after the Armistice . Four others escaped destruction by the Military Inter - Allied Commission of Control because they were assigned to " Batterie Plantagen " on coast defense duties at Swinemunde .