Intermediate work Sommo

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Plan of the Sommo intermediate plant

The intermediate structure Sommo ( Italian: Forte Sommo Alto ) was one of a total of seven barriers of the Austrian fortifications on the border with Italy . It is located on a ridge (1613 m) about four kilometers south of the village of Folgaria on the provincial border between Trento and Vicenza on the plateau of Lavarone / Folgaria. (German: Lafraun / Vielgereuth )

As the middle plant of the Folgaria blocking group, it covered the right flank of the Sebastiano plant , blocking the Orsai valley to the north and, together with the Serrada plant , the Val di Penchla with the road from Arsiero to Folgaria. It also served to secure the spaces between the Serrada plant. This was 2.5 km to the southwest on a ridge and was separated from the Sommo plant by the Val di Penchla.

Simplified representation of the interior of a tank turret with a depression mount as used at the Sommo plant. The elevation range was −15 ° to + 43 °.


On May 19, 1910, the facility was approved by the Austro-Hungarian War Ministry in Vienna , but the final artillery equipment was not yet certain at that time. Initially it was intended to install two 10 cm howitzers in armored casemates and the direction of fire towards the Serrada plant. However, this was then discarded and two tower howitzers of the TH M9 type were installed. A separate installation of the howitzer turrets to the casemate block failed because of the higher costs, so that they were ultimately placed on the casemate block. Only after the start of construction was a decision made against the installation of two 6 cm casemate cannons as traditional batteries .

  • Construction time: June 20, 1910 - September 25, 1914
  • Crew: 2 officers and 177 men
  • Construction cost: 982,000 crowns
  • Planning: First Lieutenant O. Hauenstein
  • First plant commandant: First Lieutenant Denaro, from April 6, 1915, Captain Kalifus
  • First zeroing in of the guns: September 25, 1913


Erected in concrete, it consisted of three sections - the casemate block and two infantry combat systems, - the saddle complex (S) and the back complex (R). Since there were sections in front of the plant that were not visible, it was necessary to build two advanced infantry combat plants as space between them. Between the saddle complex and the battery block was a bolt trench for infantry close defense. This was partly blasted into the rock and partly filled with concrete. It could be reached through a protected exit from the postern between complex S and the battery block. The ceiling thickness of the battery block was between 2.50 and 2.80 meters. The factory ceiling itself was reinforced in casemates with a clear width of up to 5 meters using I-beams ( also known as double T beams ). These had a thickness of NP 40 (40 cm high, 11.3 cm wide) on the top floor (i.e. directly under the ceiling). For the rooms that were smaller or deeper in the building, NP 30 or 26 beams were used (26 cm high and 11.3 cm wide) Every second of these beams was anchored with iron. Corrugated metal sheets were inserted between the girders to prevent chipped concrete parts from falling. In the outermost edge of the work ceiling, T-beams of type NP 14 were set vertically and anchored with the reinforcement bar . Due to the design, the work was not surrounded by a moat. Shortly before the outbreak of hostilities was a broad around the plant barricade of barbed wire laid.

Casemate block

The casemate block consisted of an elongated rectangle built onto the natural rock on the left and right with a protruding throat case on the left flank. There were three floors, the basement, the ground floor and the upper floor with the gun wells of the howitzer turrets. These, the rotating armored observation dome and the machine-gun armored dome above the throat case sat on the factory roof, which was protected from the weather by galvanized sheet metal. In the throat there was also a trench-like light shaft into which the window openings of the basement opened.

  • Basement

The basement had:

two food depots
a crew room
a material depot
a storage room
an engine room (generator set)
a workshop
a fuel depot
a staircase to the ground floor

At the front there was a continuous corridor from which the posternes led to the two infantry bases "R" and "S" and the postern, which was subsequently built in 1915, led to the works street as a replacement for the no longer usable main entrance.

  • ground floor

Here were:

the original factory entrance with a defensible guard casemate
the throat case with an armored dome for two machine guns to cover the throat and the rear space
a kitchen
an infirmary
a treatment room
an abortion
two crew rooms
a commanders room
a switchboard
a tomb for six coffins
a staircase to the upper floor

At the front there was a continuous corridor on the same level as the entrance area. It ended on the right at the crypt.

  • First floor
the throat suitcase with the optical signal station (connection to the Serrada plant)
two ammunition depots with ammunition lifts to the howitzer towers above
two ammunition depots
an artillery depot
two dormitories for the crew
an officer's room
an abortion
a staircase

At the front there was a continuous corridor with the stairs to the armored turrets and the observation turret. The access to the optical signal station was made from the artillery material depot.

Infantry combat plants

  • Complex "R" (back complex)

Infantry combat system, consisting of two adjacent bunkers (complex “R” on the left and complex “R” on the right) which were connected to one another and to the casemate block by a rock spar. The complex had the task of covering the invisible slope to the Val Orsara as space pranks.

  • Complex "S" (saddle complex)

Infantry combat system, consisting of two adjacent bunkers (complex “S” front and complex “S” throat) which were connected to each other and to the casemate block by a rock spar. The complex had the task of covering the access road and the slope to the Passo Coe, which was not visible from the casemate block, as a space in between.


2 × 10 cm tower howitzers THM9 on the casemate block
1 × armored casemate with two M 07/12 machine guns in complex R on the left
2 × armored domes, each with a machine gun
1 × armored dome with a machine gun in complex R on the right
1 × armored dome with two machine guns in complex R on the right
1 × armored dome with a machine gun in the S Front complex
1 × armored dome with two machine guns in the S Front complex
1 × armored dome with two machine guns in the S Kehle complex
1 × armored dome with two machine guns on the casemate block
1 × rotating observation post with a machine gun on the casemate block
1 × armored slot stand with machine gun at the exit to the infantry position

There were also:

2 × 21 cm headlight stands in complex R on the left
1 × 35 cm headlight stand in complex R on the right
1 × 21 cm headlight stands in the S Front complex


Standardization default, it should be with a detachment of the national shooters - . Regiment Trento No I occupied infantry. The planned crew was still on the eastern front, so everything that was somehow tangible was initially taken. The emergency crew for all plants initially consisted of a detachment of the kk Landesschützen-Regiment Bozen No. II , the 2nd company of the fortress artillery battalion No. 1 from Tenna (battalion commander Oberstleutnant Ludwig Pengov) and the 1st - 4th company of the fortress artillery battalion No. 8 from Haidenschaft and Wippach (battalion commander Colonel Alfred Langer). The total number of soldiers in the fort in May 1915 was 8 officers, 132 men and 56 Landsturm workers. Several standing rifle companies were in the run up for close defense. In preparation for the May offensive , an artillery staff, consisting of 25 officers and 65 men, was added. At this point in time, the structure was crowded.

Entrance area with throat case from the Sommo plant after the start of the fighting, top left the armored dome for two machine guns


In the First World War , Sommo was not attacked at all by infantry. The bombardment with artillery was rather superficial and did not cause any major damage. From May 1915, the work was occupied by two 28 cm howitzers with a total of around 1400 rounds. The bombardment was most intense in the period from August 26 to October 7, 1915. The Italians scored 712 hits on the factory premises, with only 49 shells falling on the building fabric. Of these, eleven hits were registered on the tanks, but these could not be penetrated, as was the concrete cover. On August 30, 1915, a 28 cm shell hit the armored armor of the rotating observation dome and got stuck as a dud . The tip then protruded 17 cm into the tower shaft. The dome crew was put out of action, the operator was fatally and the observer seriously wounded. It was possible to defuse the dud. After the Italians had posted a 14.9 cm field gun battery on the 7.5 km away (and abandoned by the Austrians) Col Santo (2112 m), they began to bombard the now accessible throat front of the plant. Then an earth wall was built up to the upper floor. The still unprotected windows on this floor were tried to be secured with sandbags as best they could. Since the batteries on the Col Santo could also see the factory road and the factory entrance and kept them under constant interference, a rock spot began to be driven from the cellar to a sheltered part of the road. This postern, extended by a few storage caverns and a total of 395 m long, was not completed until June 1917. The telephone and water pipes and the urgently needed fresh air also ran through them. Sommo was, like the other works of Folgariagruppe (next Sommo and work Serrada still work Sebastiano), (due to the advanced geographical position, after Maioffensive 1916 in contrast to the works of Lavaronegruppe Luserna , Gschwent and work Verle ) not disarmed . They kept their guns until the end of the war. In Sommo only the machine guns were expanded except for one.

Current condition

Due to the relatively moderate bombardment, the destruction was not as serious as with the works of the Folgaria group. Even when the steel reinforcement began to be removed from the concrete in the 1930s, the necessary blasting operations were apparently carried out more professionally than at the other plants. B. The Verle factory was completely ruined.

The facility can be entered because the inside of the right tower howitzer was made accessible by installing a staircase in the gun well .

  • See also:
Fighting on the Lavarone plateau (1915-1916)


  • Rolf Hentzschel: Fortress war in the high mountains. Athesia, Bozen 2008, ISBN 978-88-8266-516-6 .
  • Erwin Anton Grestenberger: Imperial and Royal fortifications in Tyrol and Carinthia 1860–1918. Verlag Österreich ua, Vienna 2000, ISBN 3-8132-0747-1 .
  • Rolf Hentzschel: Austrian mountain fortresses in the First World War. The Folgeria and Lavarone plateaus. Athesia, Bozen 1999, ISBN 88-8266-019-2 , ( Athesia workshop. Non-fiction book ).
  • Carta Touristica Trento-Lévico-Lavarone Kompass Fleischmann L. Istituto Geografico / Gardolo
  • Vienna State Archives / War Archives


  1. in Austria-Hungary the career group of NCOs did not exist, they were counted among the teams.
  2. both from the kk Landesschützen Regiment No. I
  3. Classification of the war for the spring of 1915 in: "Austria-Hungary's Last War" Volume II, Appendix 14..
  4. The associated post Vezzena had no artillery

Coordinates: 45 ° 53 ′ 30 ″  N , 11 ° 12 ′ 2 ″  E