's K5 series were consistent in mounting a long gun barrel in a fixed mounting with only vertical elevation of the weapon. This gondola was then mounted on a pair of 12-wheel bogies designed to be operated on commercial and military rails built to German standards. This mounting permitted only two degrees of horizontal traverse. The carriage had to be aligned on the rails first, with only minimal fine leveling capable once halted. Hence the gun could only fire at targets tangential to an existing railway track. To track targets needing greater traverse either a curved length of railway was used with the gun shunted backwards or forwards to aim; a cross-track was laid with the front bogie turned perpendicular to the rest of the gun and moved up and down the cross-track to train the weapon; or for 360 degree traverse, the "Vögele Turntable" could be constructed, consisting of a raised rail section carrying the gun, running on a circular track with a central jack to raise the gun during traverse and to take some of the enormous weight. The main barrel of the K5 is in calibre, and is rifled with twelve grooves. These were originally deep, but were made shallower to rectify cracking problems.
History
The K5 was the result of a crash program launched in the 1930s to develop a force of railway guns to support the Wehrmacht by 1939. K5 development began in 1934 with first testing following in 1936 at Darlowo in the former Farther Pomerania at the South coast of the Baltic Sea. Initial tests were done with a 150 mm barrel under the designation K5M. Production led to eight guns being in service for the Invasion of France, although problems were encountered with barrel splitting and rectified with changes to the rifling. The guns were then reliable until the end of the war, under the designation K5 Tiefzug 7 mm. Three of them were installed on the English Channel coast to target British shipping in the Channel, but proved unsuccessful at this task. Two K5 guns, named "Robert" and "Leopold" by German crews, were shipped to Italy to help counter the American landing at the town of Anzio in February 1944. The Allied soldiers stuck on the beach nicknamed the two German guns "Anzio Annie" and "Anzio Express" due to the express train-like sound the shells generated. On 18 May 1944 the guns fired off their remaining ammunition and then escaped along the coastal railroad into the rail yard in Civitavecchia, in preparation for evacuation. This proved impossible and the guns were destroyed by their crews. Towards the end of the war, development was done to allow the K5 to fire rocket-assisted projectiles to increase range. Successful implementation was done for firing these from the K5Vz. A final experiment was to bore out two of the weapons to smoothbore to allow firing of the Peenemünder Pfeilgeschosse arrow shells. The two modified weapons were designated K5 Glatt. Several other proposals were made to modify or create new models of the K5 which never saw production. In particular, there were plans for a model which could leave the railway by use of specially modified Tiger II tank chassis which would support the mounting box in much the same manner as the railway weapon's two bogies. This project was ended by the defeat of Germany.
Projectiles
Two types of high explosive projectile were used with the K5. The 28cm G35 weighed and contained a charge of of TNT. The 28cm Gr.39 m. Hbgr. Z. was slightly heavier, weighing and containing around of TNT. These projectiles were pre-rifled with angled splines along their midsection which were aligned with the guns rifling before firing. The rocket assisted projectile was known as the 28cm R. GR.4351. This carried of explosive and was boosted by around of double-base powderrocket propellant. The total weight was. 19 seconds after firing the rocket motor was ignited and the projectile was accelerated through the stratosphere. When the rocket burnt out the center section containing the rocket motor fell away and the projectile continued on its course. The maximum range for this projectile was but due to the weight of the rocket motor the projectile carried less explosives.
Surviving guns
A K5 is preserved at the United States Army Ordnance Museum in Fort Lee. Leopold was shipped to the United StatesAberdeen Proving Ground, where it underwent tests and evaluations. In early 2011 it was moved to Fort Lee, Virginia as a result of the 2005 Base Relocation and Closure Act. The guns were discovered on a railroad siding in the town of Civitavecchia, on 7 June 1944, shortly after the allies occupied Rome. Robert had been partially destroyed by the gun crew before they surrendered and Leopold was also damaged but not as badly. A second surviving gun can be seen at the Batterie Todt museum, near Audinghen in northern France.
