During World War 1, the Krupp concern - a German industrial steel and weapons manufacturer - produced large caliber railway guns for the German Army. Their most notable creations during that span became the "Paris Gun" and large siege howitzer "Big Bertha". By the 1920's, the German military was under revitalization and the German Army met with Krupp to discuss the need for new railway guns that could be transported across established rail networks in Germany and throughout Europe if need be. The German Army sought a new generation of large-caliber guns that could prove more decisive through improved accuracy at longer ranges. The Paris Gun of World War 1 could shoot a large projectile some 70 miles out but needed the target to be the size of a city when the shell landed a mile or two "off the mark". Big Bertha was powerful enough against fortifications with her 2,200 pound shells but she inherently lacked the distance needed to contend with targets farther than 9 miles. The Paris Gun ended up being more of a psychological tool against Parisians while the Big Bertha was tactically limited on the battlefield.
The German Army understood that it could use their extensive railroad network in Germany to good effect and the situation outside of Germany would also be favorable when it came time to maneuver the gun to a new position in France, Belgium, Holland and beyond. These railway guns could cover longer distances that the slow and plodding nature of self-propelled guns attached to the land army. The result would therefore be a relatively mobile artillery piece with a lethal firing capability that could be more than a psychological tool against the enemy.
The development of a new heavy rail rifled gun system - the "K5" - was started by Krupp in the late 1920's and, by 1934, the project resulted with a prototype barrel having a 120mm bore. Naturally, the gun barrel was specifically designed to be transported by railcar and was further mounted on a gondola that rested atop 2 x six-axle, twelve-wheel bogies - one on each end. Both ends of the gondola were stationed directlyabove and between the third and fourth axles, the exact center of each six-axle bogie, for maximum weight distribution of 436,000 pounds - the price to pay for such a heavy weapon system.
During development of prior smaller railway gun systems, construction involved a pivot mounting which allowed the gun to fire in any direction relative to the line of track it sat upon. Firing of these smaller guns would rock the gun carriage while on the tracks so stabilizing outriggers were added to prevent the gun from tipping over and off of the tracks themselves. Larger guns like the K5, limited by their sheer weight, could therefore only move one degree of traverse along the horizontal and had an elevation arc of +50 degrees. For firing more off of the weapon's centerline, a curved section of track was needed. For full 360-degree fire, a roundabout turntable was used to aim the gun in any direction. Due to the gun's minimal traversing nature, it became necessary for German Army engineers to construct special track sections from the commercial railway system at predetermined locations well in advance of the planned fire missions.
At its core, the K5 railway gun held an effective range out to 40 miles and was extremely accurate due to the rifled barrel (as opposed to smoothbore, which does not spin the projectile in the barrel prior to exiting). The rifling was reduced to 12 x 7mm deep grooves after testing indicated the barrel was cracking with the original 10mm deep grooves. The high explosive shell alone weighed some 562lbs (255kg) and was 288mm in caliber. Shells and the required cordite powder bags were stored away from the gun for safety. Each K5 railway battery consisted of two guns with each gun on its own train while a third train was required to transport the required gunnery staff, security detachment (to prevent sabotage or overrun by enemy infantry), administrative personnel, mechanics (for the guns, trains and trucks), cooks and assorted non-military personnel. In all, this amounted to approximately 85 personnel. Each of the three trains required two locomotives each, one at each end of the line, to move the guns as well as standard passenger and sleeper cars along with specialized refrigerator cars for the cordite and freight cars for the large amount of shells and equipment needed to support the battery during deployment.
The battery crew consisted of 42 trained artillery officers and enlisted personnel. An artillery officer and 24 men were assigned to operate and fire the gun proper. A crew of 8 would manage the shells, setting the timing fuses in each shell and transporting the projectiles along a cart from the storage railcar to the gun. A set of smaller gauge track was laid from the car to the gun to help support the cart used to haul a single shell. Powder bags were raised by a hoist on the gun platform itself. The crew on the firing platform required 2 men to be stationed on the rear of the gun and these personnel would manage the hoist needed to lift the shell and powder from the awaiting cart at ground level. The hoist then lowered the shell and powder into the breech of the gun. Six crewmen were needed to complete this manual process. Others maintained duties on the ground related to the firing of the gun and electrically-assisted elevation mechanism. Still others would remove the shells metal jacket once it was fired and throw the spent casings to the ground to be reused again. Electricians were assigned to monitor and maintain a large generator that was itself required to power the electrical system meant for firing and elevating the K5 barrel.
The German military utilized two types of locomotives during transport of K5 systems - one of steam power and the other diesel-fueled. The standard locomotive used by the German Army for basic transport during most of the war (and for its civilian passenger trains of the time) was the steam engine. Steam engines proved readily available and cheaper to operate than their diesel counterparts and were used in many missions to move K5s to firing locations. Once deployed, the engine of choice was the diesel locomotive model WR360C14. The battery crew preferred diesel-fueled engines over that of steam due to the white smoke produced when the steam engine released pressure, making the train (and gun) easy to spot from the air. As the war continued and the Allies acquired complete air domination, steam engines were easy targets for strike aircraft so natural concealment was utilized in the form of railway tunnels. An enemy aircraft could also destroy track sections but track could be quickly repaired. One of the interesting design qualities of the K5 system was its suspension system which allowed the train to cross over hastily or poorly laid track.
K5-related train engines and car sections were typically painted over in camouflage schemes to help blend them into natural covering as much as possible. The first four production guns, however, were completed in a dark gray coat at the factory in 1937. As deployments were officially ordered, brown was then added to the existing grey. When K5's were formally sent to the Eastern Front in the Soviet Union, the paint scheme was applicably changed to white for the expected winter campaign. Guns delivered to the West Front in France were grey and those scheduled for the Afrika Korps in Africa were painted a dark motley desert yellow.
Once delivered to a firing location, the K5 was set up to fire on a predetermined target of interest. For targets that were mobile, this naturally proved to complicate K5 functions foring German Army railroad engineers to use multiple in-the-field methods to allow the gun to fire on both moving and stationary targets. If time permitted, the rail crews could lay curved track at the firing point, allowing the diesel engine to move the gun in a horizontal fashion. However, the turntable ultimately became a necessity for the K5 and other like-large artillery railway guns. This heavy platform was specifically made for the gun to rest on it while allowing the system to be turned and traversed 360 degrees and vertically up to 50 degrees. Eventually a portable turntable was devised for transport with the K5 battery train. When the Wehrmacht captured territory in Europe, they took whatever usable war equipment was left behind by their enemies - including valuable train yard turntables left behind at coastal areas by retreating French and Belgian armies.
By the time of the invasion of France, eight K5 "Tiefzug" guns had been completed and three were shipped to the east along the French coast. In July of 1940, the guns were installed on captured French turntables facing the English Channel coast line. The six K5's were targeting inland targets along the British coastline as well as shipping in the Channel. Allied warships were unable to close in and fire against these K5's due to the 40mile range of its gun. A number of merchant ships were therefore sunk and British shipping were forced to sail at night - prime pickings for the German U-boat fleet. The German Luftwaffe supplied cover to the vulnerable K5's from the air, defending against attack by British warplanes.
Two K5 guns were shipped to Italy to help counter the American invasion at the town of Anzio in February of 1944. By early March, these K5's - named "Robert" and "Leopold" by German crews - were stationed in the Alban Hills above the beachhead and port area. From this vantage point, the two K5's rained large-caliber shells down on the seven divisions of 70,000 Allied troops - including the US 36th Infantry Division - trying to break out of the established beachhead. The invasion stalled and the surrounding lands became reminiscent of trench warfare consistent to World War 1. Additional air power was supplied by screeching Junker Stuka dive bombers. During the months of the Anzio Campaign, Allied VI Corps suffered 4,400 killed, 18,000 wounded and 6,800 missing or captured. 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 when passing by.
Improvements to the K5 family line continued through to the end of the war. There was always attempts at increasing her range so a smaller shell - the Raketen Granate 4331(RGr 4331) - was designed. This projectile attached a cast-propellant rocket motor in the nose section of the shell that would propel it to a range of 54 miles. However, at such ranges, the shell's overall accuracy was somewhat diminished. Again trying to improve accuracy, six K5 Vz multi-grooved barrel guns were produced that could fire iron-banded shells. Another option included the K5 "Glatt" that used an "arrow" shell needing a large 31cm smooth-bored barrel - only two of the type were produced. In 1943, the air war had shifted in favor of the Allies and so the German Army felt the K5 should be converted to a self-propelled gun system using the PzKpfw Tiger heavy tank chassis. This caravan would need five tank chassis to simply move the gun - two chassis would carry the firing platform while another two would carry the barrel and one more managed the breech group. Also required were a number of trucks to carry staff, supplies, shells and powder. The development was not completed by wars end. Additional planned upgrades to the family line were also not followed through for long-range terror weapons such as the V-1 and V-2 rockets were beginning to take a greater hold on priorities and offered much more in terms of capabilities and resulting destruction.
On June 7, 1944, as the American Army moved out of Anzio, the two abandoned K5 guns were found and confiscated. Both guns and associated shells were loaded onto awaiting USN ships and sent to the United States Army Ordnance Museum at Aberdeen, Maryland. "Robert" was deliberately damaged by retreating German troops though "Leopold" was found to be in better shape. The Army put together one of the guns and used it for firing tests. The K5 remained at Aberdeen until 2010 where it was broken down and trucked to its new home at Fort Lee, Virginia along with most of the existing Aberdeen exhibits.
Despite its limitations and optimistic expectations, "Anzio Annie" was perhaps the most successful railroad gun of World War 2.