A railway gun, also called a railroad gun, is a large artillery piece, often surplus naval ordnance, mounted on, transported by, and fired from a specially designed railway wagon. Many countries have built railway guns, but the best known are the large Krupp-built pieces used by Germany in World War I and World War II. Smaller guns were often part of an armoured train.
Railway guns have been rendered obsolete by advances in technology. Their large size and limited mobility make them vulnerable to attack, and similar payloads can be delivered by aircraft, rocket, or missile.
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The design of a railroad gun has three issues over and above those of an ordinary artillery piece to consider. Namely how the gun is going to be traversed - i.e. moved from side to side to aim; how the horizontal component of the recoil force will be absorbed by the gun's carriage and how the vertical recoil force will be absorbed by the ground.
The first method of traverse is to rely entirely on movement along a curved section of track or on a turntable with no provision to traverse the gun on its mount. The second is to traverse the rail car body on its trucks, known as a car-traversing mount. Generally this is limited to a few degrees of traverse to either side unless an elaborate foundation is built with a center pivot and traversing rollers. The design of the foundation is the only limit to the amount of traverse allowed in this latter case. The third choice is to allow the separate gun mount to rotate with respect to the rail car body, known as a top-carriage traversing mount. This usually requires the gun to be mounted on a central pivot which, in turn, is mounted on the car body. With few exceptions these types of mounts require some number of outriggers, stabilizers, or earth anchors to keep them in place against the recoil forces and are generally more suitable for smaller guns. The American post-World War I assessment of railroad artillery considered that the utility of even a small amount of traverse for fine adjustments was high enough that either of the two latter traversing methods is preferable to a fixed mount.[1]
There are four primary methods to absorb the recoil force for railroad guns: cradle recoil, top-carriage recoil, sliding recoil and rolling recoil.
Cradle recoil means that the gun recoils backward in its cradle, retarded and stopped by hydraulic buffers. It is returned to battery, or the firing position, by either helical springs or by air in a pneumatic recuperator cylinder that is compressed by the force of recoil. This is the most common method used for lighter railroad guns and for virtually all field artillery designed after the French introduced their Canon de 75 modèle 1897.
Top-carriage recoil is where the gun is mounted in an upper carriage that moves on wheels on fixed rails. The gun and upper carriage recoil together, restrained by the usual hydraulic buffers. Return to battery is effected either by gravity, through the use of inclined rails, which the gun and carriage have run up, by springs, or even by rubber bands, on some improvised mounts.[2] It is not well-suited to firing at high elevations because it can't absorb much of the vertical component of the recoil force.[3]
Sliding recoil has the car body sitting on a set of wooden crossbeams or "sleepers" placed underneath it which have been jacked down on to a special set of girders incorporated into the track so that about half the weight of the mount has been transferred to them from the trucks. The gun, car body and trucks all recoil together with the friction generated by the crossbeams sliding on the girders absorbing the recoil force after moving only about 1 to 2 metres (3.3 to 6.6 ft) to the rear. The sleepers must be jacked up again to allow the gun to roll forward to its firing position. This was often done by handwheels driving gear trains attached to the wheels, or even by electric motors on more modern mounts. Almost all of these type of mounts were of the non-traversing type and had to be fired from a curved section of track or turntable. The American post-World War I assessment of railroad artillery praised its ruggedness, ease of manufacture and convenience in service, but acknowledged its unsuitability for smaller guns, due to excessive time of operation and lack of traverse, and that it was not suitable for the largest howitzers firing at high angles because of the enormous trunnion forces.[3]
With rolling recoil the entire gun, mount and everything rolls backward, typically between 30 to 50 feet (9.1 to 15 m), restrained only by the brakes. The mount was winched back into firing position by cables fastened to the track. This system was usually combined with cradle recoil because the springs of the trucks cannot withstand the vertical component of the recoil force alone. This type of mount was usually fitted with car-traverse. It was unsuitable for smaller guns due to the lack of traverse.[3]. The great advantage of this method is that it requires minimal preparation and can fire from any suitable section of curved track.[4]
The methods were often used in combination with each other. Examples include the French 520 mm (20 in) railway howitzer which used cradle-sliding recoil. The American 14"/50 caliber railway gun Mark II used cradle-rolling recoil as did the British 14 and 12 inch railway guns. Only the oldest weapons used a combination of top-cradle and sliding recoil. One example being the earliest mounts for the British BL 9.2 inch Railway Gun.
The combination of rolling and cradle-recoil methods absorbed both the horizontal and vertical components of the recoil force and needed no special preparations, but all other types required some method to transmit the vertical force to the ground. One way is to build a platform on either the ties or the ground with girders, beams, pads or floats. The horizontal component would be alleviated by either sliding recoil or rail clamps, guys or struts to secure the mount in place. The French Schneider 194 mm (7.6 in) and 240 mm (9.4 in) mounts and the British 9.2 inch guns and 12 inch howitzers used rail clamps or guys. The American 8 in (200 mm) gun and the French 240 mm Canon de Mle 1893/96 M used struts.[4]
The other method is build a firing position and recoil pit (épi de tir in French) underneath the tracks, using either heavy timbers like the French 340 mm (13 in) and 400 mm (16 in) howitzers or an elaborate concrete or steel base. These latter were mostly used by the Germans for the 21 cm (8.3 in) and larger railroad guns and by the French for their Batignolle mounts. Generally, for these emplacements the rails merely served to guide the gun into position and the gun was often mounted on a central pivot to allow up to 360° of traverse. The primary drawback of these positions was the lengthy time to build them.
The idea of railway guns appears to have been first suggested in the 1860s by a Mr Anderson, who published a pamphlet in the United Kingdom titled National Defence in which he proposed a plan of ironclad railway carriages. A Russian, Lebedew, claimed to have first invented the idea in 1860 when he is reported to have mounted a mortar on a railway car.
The first railway gun used in combat was a banded 32-pounder Brooke naval rifle mounted on a flat car and shielded by a sloping casemate of railroad iron. On 29 June 1862, Robert E. Lee had the gun pushed by a locomotive over the Richmond and York River line (later part of the Southern Railway) and used at the Battle of Savage's Station to interfere with General George McClellan's plans for siege operations against Richmond during the Union advance up the peninsula.[5] Photographic evidence exists of at least one Union 13-inch siege mortar mounted on a rail car during the Siege of Petersburg. It was nicknamed the Dictator or the Petersburg Express.[6] Another photo exists of a gun mounted on an armored rail car with the caption of "Railway battery used in siege of Petersburg" although no textual evidence survives in support of the caption, which makes the claim that it is a photo of the Confederate gun from 1862 dubious.
France also used improvised railways guns during the Siege of Paris in 1870 and the United Kingdom mounted a few 4.7 in (120 mm) guns on railway cars which saw action during the Siege and Relief of Ladysmith during the Second Boer War.[7] A 9.2 inch gun was taken from the Cape Town coast defenses and mounted on a rail car to support the British assault on Boer defences at Belfast, north-east of Johannesburg, but the battle ended before it could get into action.[8]
In France, Lt. Col Peigné is often credited with designing the first railway gun in 1883. Commandant Mougin is credited with putting guns on railcars in 1870. The French arms maker, Schneider offered a number of models in the late 1880s and produced a 120 mm (4.7 in) gun intended for coastal defense, selling some to the Danish government in the 1890s. They also designed a 200 mm (7.9 in) model for Peru in 1910, but they were never delivered.[9]
The outbreak of the First World War caught the French with a shortage of heavy field artillery. In compensation, large numbers of large static coastal defense guns and naval guns were moved to the front, but these were typically unsuitable for field use and required some kind of mounting. The railway gun provided the obvious solution. By 1916, both sides were deploying railway guns.
Baldwin Locomotive Works delivered five 14"/50 caliber railway guns on trains for the United States Navy during April and May 1918. Each train transported and supported a Mk 4 14"/50 caliber gun,[10] a 14 in (360 mm) naval rifle used on New Mexico and Tennessee class battleships, mounted on a rail carriage with four 6-wheel bogies. The locomotive, ammunition cars, supporting equipment cars, and accommodation cars for the crew were under the command of a United States Navy lieutenant, and under overall command of Rear Admiral Charles Peshall Plunkett. After delivery by ship, these trains were assembled in St. Nazaire in August[11] and fired a total of 782 shells during 25 days on the western front at ranges between 27 and 36 kilometres (30,000 and 39,000 yd). The railway carriages could elevate the guns to 43 degrees, but elevations over 15 degrees required excavation of a pit with room for the gun to recoil and structural steel shoring foundations to prevent caving of the pit sides from recoil forces absorbed by the surrounding soil. The train included cars to transport recoil pit foundations constructed by Baldwin.[12] One of these guns is on display outside the museum at the Washington Navy Yard.
Baldwin constructed six similar gun carriages and two of an improved Mk II type[10] designed to permit firing the gun at all elevation angles without transferring weight to a separate foundation. These eight guns were completed too late to see combat, although some were stationed through World War II in special coast defense installations at San Pedro, California (near Los Angeles) and at the Panama Canal Zone where they could be shifted from one ocean to the other in less than a day. Improved carriages were designed to allow transport to several fixed firing emplacements including concrete foundations where the railway trucks were withdrawn so the gun could be rapidly traversed (swiveled horizontally) to engage moving ship targets.[13]
The United States constructed approximately fifty smaller depressed center railway carriages on two 6-wheel bogies for 8 inch (203 mm) naval rifles made surplus by the Washington Naval Treaty.[14] Approximately a dozen of these were used for the defense of Oahu. Others were stationed through World War II for coast defense of Manila, Bermuda, Newfoundland, Puget Sound, the Columbia River, Chesapeake Bay, Delaware Bay, and Fort Hancock, New Jersey (near New York City).[15]
In 1930 the US Army tested 12 inch mortars that were train based that could be moved to different locations of the country in a time of crisis. [16]
Schneider of France developed the Obusier de 520 modèle 1916, a 20 inch (520mm) railway "Fort Buster" to do what the German 16" Big Bertha had done at the outbreak of ww1 but to reduce the German forts in the final line of German defences. One was destroyed in trials and the other did not complete firing trials prior to the signing of the Armistice. The gun remained in storage and was captured by the Germans during World War II. It later formed part of the German artillery complement during the Siege of Leningrad. The gun was disabled by a premature detonation and later abandoned.
The Second World War saw the final use of the railway gun, with the massive 80 cm (31 in) Schwerer Gustav gun, the largest artillery piece to be used in combat, deployed by Germany. The rise of the aeroplane effectively ended the usefulness of the railway gun. Similar to battleships, they were massive, expensive, and, in the correct conditions, easily destroyed from the air.
Both Germany and Great Britain employed railway-mounted guns that were capable of firing across the English Channel between the areas around Dover and Calais.[17] Germany employed a number of 40 cm guns. Britain employed three 13.5-inch (342.9 mm) railway mounted guns on the East Kent Light Railway, located around Lydden and Shepherdswell.[17][18][19] These were known as Gladiator, Sceneshifter and Piecemaker.[17] 9.2 inch Mark 13 guns were located near Canterbury and Hythe; an 18 inch Howitzer, Boche Buster, sited on the Elham Valley Railway, between Bridge and Lyminge; and 12 inch howitzers, Mk 3 and 5, located around Guston.[17]