15-cm-sIG 33 (15cm těžké pěchotní dělo)

heavy infantry protection
Caliber: 149.1mm
Barrel length: L/11.4 (1700mm)
Weight: 1800 kg or 1680 kg (moto or hipo traction)
Muzzle velocity: 240m/s HE (280m/s with lightweight filling)
Range: 4700m
Firing rate: 3 rounds/min.
Bullet weight: 38kg (HE) 24.5 lightweight
Possibility to fire over - caliber missiles (Stielgranate 42
Production: AEG-Fabriken Berlin Henningsdorf, ČZ Strakonice
The most effective German infantry cannon, construction commissioned in 1927, taken over in 1933, in production from 1936 to 1945. Chassis originally all-steel since 1938 in combination with light metals.

1 photo :September campaign somewhere in Poland
2 photo: Second Warsaw Uprising
3 photo: SiG with Stielgranate 42 artillery shell
6 photo: Cannon captured by the Red Army in the USSR autumn 1941

The fighting on the front of World War I led to a revision of many tactical procedures in the German army. After breaking the German offensive in 1914 in France and tempting the troops to positional trench warfare, it was a great surprise to the command of the Imperial German Army. The army suddenly came to the startling realization of how much power there could be in combining infantry and artillery for self-defense and how little effective they could be in attack.
The greatest problem for the attacking infantry was the silencing of the defensive machine-gun firing positions that were wreaking havoc in the ranks of the attacking troops. Even several hours of artillery preparation preceding an infantry attack could not disable all the machine gun nests. Attacking units usually took heavy casualties in such attacks.
The command of the Imperial Army adopted as the only rational solution the arming of the infantry with a heavy accompanying weapon: light cannons, which were to lead the fire directly or by an upper group of angles. In the latter case, the army wanted the infantry to be supported not only by heavy mortars of 250 and 170 mm calibre. Therefore, a 76 mm mortar was constructed in a relatively short time. By March, the German army already had 1,345 of them. The mortars were used with success to destroy the enemy's attacking live force, but the results in supporting their own attacking troops were very questionable. Therefore, it was suddenly clear that the army needed a simple infantry gun that could effectively destroy enemy machine gun nests. The weapon had to meet the requirements of ease of operation, it had to be lightweight so that it could be easily moved on the battlefield. By 1918, the Krupp company could not deliver a gun that met the demands of the German army.
Despite the Treaty of Versailles, Krupp and Rheinmetall were developing a new gun. In the 1920s, there was a vigorous discussion in specialized army journals in Germany about the strategic and technical requirements for an infantry support gun. The influence and development of the tank and the threat of the tank to the infantry were also considered. The universal gun, which was also adapted for firing against tanks, appeared very attractive. But to obtain a horizontal trajectory and high muzzle velocity, the gun would have to have a relatively long barrel, which in turn would make it difficult to fire the upper group of angles against an enemy hidden behind terrain irregularities (hills) or in built-up areas. Eventually it was recognized that the main purpose of infantry guns was to provide immediate support to infantry formations during both attack and defense. The destruction of armoured targets was to fall to the regimental anti-tank gun unit.
In the second half of the 1920s, the development of new types of guns was abandoned, which were to become the main guns in the regiments of the German infantry. In 1927, the 7.5 cm leichtes Infanteriegeschütz 18 [leIG 18] light infantry gun was adopted into the German Army. And at the same time as this gun, Rheinmetall designed a heavy infantry gun of 150mm calibre. However, it was not adopted into armament until 1933. The choice of arming regimental artillery with a weapon of this calibre on such a scale was a novelty in the world. Thanks to the Schweres Infanteriegeschütz 33 [sIG 33] guns, German regiments had a substantial fire superiority at the beginning of the war. German regiments gained the ability to destroy and silence enemy artillery positions at relatively long range, but they could also destroy fortified defensive positions well.
The Schweres Infanteriegeschütz 33 [sIG 33] is of conventional design. The barrel is 1,700mm long ( L/11.4 with a calibre of 149.1 mm, without muzzle brake. The barrel was wedge-shaped with a horizontal wedge. A hydropneumatic brake device was mounted in a peg under the barrel, the sIG 33 boasted a fairly solid box magazine, a two-wheeled "single-tail" from the perspective of the German designers. The protective shield was placed in front of the wheels as with the leIG 18, this allows the maximum angle of square to be achieved. Two spring dampers were placed on the sides of the receiver to distribute the weight of the heavy barrel evenly when firing.
The firing range was 11.5° to the left and right and the aiming range was -4° to +75°. A Rundblick-Fernrohr ZE 34 sight was used. The gun had cast steel wheels with rubber bandage. The version for moto traction weighed 1,800kg in combat position and 1,825kg in marching position. As for the Hipo versions, which had to be pulled by 6 horses, they weighed 1680-1700kg.
The crew of each sIG 33 gun consisted of 7 people. The necessary time to prepare for opening fire within the regiments was 45 minutes. The maximum firing frequency was 2 -3 rounds per minute.
The dimensions of the gun are:
Length: 4 300mm
Width: 2 150 mm
Height: 1 650 mm
During World War II, the most commonly used ammunition was:


15cm IGr 38 - three-hole grenade with a total weight of 18kg, load (anatol) 8.3kg
15 cm IGr 38 Nb - smoke grenade weighing 40 kg
15 cm IGr 39 HL/A - cumulative, weighing 24.6 kg, filled with hexogen, penetrated armour 160 mm thick at 1000 m
15 cm Stielgranate 42 - a supercaliber missile, weighing 89.5 kg, filled with 27 kg of anatole, This munition was widely used for destroying fortified defensive positions, ambushes, and for building roads in minefields

Otherwise, six fragmentation grenades were developed for the gun, depending on the strength of the 15 cm IGr 33 and 38 charge:
They could be fired at a distance:
1 475 m charge no. 1, initial velocity 122 m/s
up to 4700 m [charge 6, initial velocity 240 m/s].
Series production of the guns started in 1933 at Rheinmetall ( I have come across some reputable works with the year 1936). The price for one gun was 20 450 Reichsmarks. For comparison I give the prices of some other guns, 7,5 cm leIG 18 cost 6700 RM, 10,5 cm leFH 18 16400 RM, heavy field howitzer 15 cm sFH 18 - 38500 RM.
The guns were mass produced until 1944. In the years of World War II, however, it was also produced by AEG in Berlin (Henningsdorf) and also by Böhmische Waffenfabrik (from March 1939 by the Praga - Česka Zbrojovka Strakonice concern). Already during the tests on the artillery polygon the company was warned about the large weight of the sIG 33, which made it difficult to manoeuvre on the battlefield. The gun was judged on the whole good, as an effective weapon, harmless and durable, but too heavy for infantry purposes. By the late 1930s it was possible to use lightweight metals to make the gun's breech, resulting in a 150kg reduction in weight. However, only a small number of such modernised guns reached the troops. During the war, due to a shortage of light metal alloys, the manufacturer reverted to using the original shells. In September 1939, 410 guns of the sIG 33 were available to the German army. At the beginning only 35 divisions of the I wave and 16 divisions of the II wave received the sIG 33 gun. In the divisions of the following waves, only light guns leIG 18 were armed.
In each infantry division of the 1st and 2nd waves in each of the three regiments there was a separate 13th infantry gun unit, armed with 6xleIG 18 and 2x sIG 33. Thus, in total there were 18 leIG 18 and 6xsIG 33 in the division.
The artillery unit had a total of 180 officers, NCOs and soldiers and had 133 horses. Officers and NCOs moved around on horseback, while the remaining men rode on the front of the guns or on ammunition-carrying vehicles. The commander of the unit most often had the rank of captain.
From 1943 onwards, some units were armed with 120mm calibre sGrW 42 heavy mortars. One of the reasons for the introduction of this armament, was the fact that the industry was not sufficient to supply heavy guns, the production of the sGrW 42 was very simple, one mortar cost only RM 1,200!


My source is :
Mariusz Skotnicki "Nowa Technika Wojskowa" Nr 10/2002

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