Historic context :
At the end of 1914, the West Front freezed in static entrenched lines, and the fighters adapted themselves to the trenches warfare. The German Minenwerfers proved excellent for this kind of operations, but are not numerous enough yet despite RheiMetall efforts, and several companies proposed substitution solutions.
The Firma Heinrich Lanz & Co from Mannheim was specialized in agriculture engines and systems. At the start of 1915, it proposed a light Minenwerfer strongly inspired from the Mauser Minenwerfer appeared at the end of 1914, but with numerous improvements that will turn this '9 cm glatter leichter Minenwerfer Lanz' into a succesful weapon.
Keeping the Mauser 91.3 mm caliber, the tube was now thicker and stronger, made in cast and machined steel, allowing the use of the more powerful smokeless gunpowder. The breech was also made stronger and had better closing up properties. It was still removable and equipped with a handle, but the rustic strong safety pin closing system was replaced by a 90 degrees rotation and screws locking system. The light 4 legs steel bars trestle had become foldable for the transport. Even the platform, still in wood, was improved with 9 planks and more space for accessories.
The munitions too were improved. The Lanz light Minenwerfer fired machined cast iron projectiles of a typical shape with two thicker rings. Thes high explosive shells ('GranatMine') existed in a time version (with a wick system) and in a percussion version. This latter version used a new and smart 'Pappenberg' fuze allowing the explosion of the shell whatever was the projectile landing angle. This fuze was to be used with other weapons afterwards. The Lanz mortar was also able to launch the cylindric procetiles ('stove pipes' - 'gl. leichte WurfMine') of the Mauser mortar, as well as chemical ammunitions.
All these improvements applied to the weapon and its ammunitions, definitely made the Lanz mortar more performing than the Mauser, at the cost of a wight increase. It will be adopted by the Austro-Hungarian Army in 1917 as a replacement of its 9cm MW M14/16 (400 weapons ordered).
Technical data :
- Complete description : 9cm Lanz smoothbore light trench mortar
- Design year : 1915
- Calibre : 91.30 mm
- Weight in firing position : 109 kg
- Weight for transportation : idem, separable in two loads : 60 kg for the tube and breech, 45 kg for the mounting and the wooden base
- Tube length in calibres : 0.00
- Grooves : 0 smooth bore
- Projectile weight : 3.95 kg (GranatMine) / 3.30 kg (gl. leichte Wurfmine)
- Initial speed :
- Fire rate :
- Range : 450 m (GranatMine) / 320 m (gl. leichte Wurfmine)
- Elevation range : 45 to 75 degrees
- Direction range : none