Maryland War Memorial Plaza
Lat : 39.29130 / Long : -76.61980
General comments on this surviving gun :
Identical items in the same location :
Items covered by this file :
Historic context :
The close combats of Port Arthur siege, during the Russia / Japan war in 1904-1905, gave to the whole world observers and military analysts important lessons that influenced the evolution of numerous weapons that were used afterwards during WW1.
This is how the improvised techniques used by Japaneses in order to bring or launch heavy explosive charges on the Russian close defences or fortifications inspired the German pioneer engineers the need of adding to the powerful heavy mortars of the classical artillery more mobile small mortars able to shoot precisely at short range high power shells in order to destroy specific obstacles or deep entrenchments.
This need was understood by the weapons industry, and in 1909 Krupp proposed a weapon named '5.3cm BombenKanone L/19' that was able to launch at a distance of 300 m projectiles of 85 kg made of a sphere ant a 53mm diameter tail, while Rheinmetall was working on a mortar launchning classical ogival shape 100 kg projectiles at the distance. The German Pionneers soon decided to follow RheinMetall ideas and that company was ordered to study and manufacture a whole range of 3 trench mortars (named 'MinenWerfer', litteraly 'mine launchers') of different calibres.
The 250mm heavy model appeared first in 1910 and was tested until 1911, date when it started to equip the Pioneers units specialised in the siege warfare. This '25 cm sMW, ' ('sMW' = 'schwerer MinenWerfer' = heavy mine launcher), later named '25 cm sMW a/A' to differenciate it from the improvement appeared in 1916 ('a/A' = 'alte Art' = Old version), was a modern weapon, equipped with recoil recuperators, a rifled barrel (6 grooves), muzzle loaded and using separate propulsive charges that were fired by a friction primer (later electric) inserted at the gun base.
The power of its big 97 kg bombs was huge, helped by the slow initial speeds that allowed to decrease the shells wall thickness and therefore increase the explosive material proportion in the shell to an unusual 50% ratio.
The availability of 44 such weapons in the German Army at the war outbreak was a total surprise for the Allies. The first shots took place on August 13th 1914 on the Fléron Fort near Liège and caused the fall of this position. Other famous achievements occured soon later and contributed to the fall of the forts of the fortified towns of Liège, Namur and Antwerp in Belgium, and Maubeuge in France. This weapon confirmed even more its extreme utility from the early beginning of the positions war at the end of 1914, for the destruction of entrenchments, shelters and surface obstacles.
There were 188 such mortars in the armies in the end of 1915.
Technical data :
- Complete description : 25cm Middle trench mortar old mark
- Design year : 1910
- Calibre : 250.00 mm
- Weight in firing position : 660 kg
- Weight for transportation : 955 kg (with the 232 kg platform and the wheels)
- Tube length in calibres : 3.00
- Grooves : 6 34.44 mm wide; 7 degrees angle
- Projectile weight : 97 kg (mine raccourcie 70 kg)
- Initial speed : 51 m/s (73 m/s for the short mine)
- Fire rate :
- Range : 563 m (750 m for the short mine)
- Elevation range : 45 to 75 degrees
- Direction range : 20 degrees total range