The 10.5cm SK L/40 Naval Gun

10.5cm SK L/40 from the SMS Emden on display in Hyde Park, Sydney, Australia
Photo by Bukvoed on Wikimedia

The naval arms race between Britain and Germany in the late 19th and early 20th centuries as pursued by the German emperor, Kaiser Wilhelm II and put into practice by Admiral Alfred von Tirpitz demanded the very best in naval firepower of the day. In the case of cruisers such as the SMS Königsberg and SMS Emden, this was the 10.5cm SK L/40.

Specifics of the 10.5cm SK L/40
The main armament of the SMS Königsberg came in the form of ten quick firing heavy guns, the Krupp 1905 model 10.5cm Schnellladekanone Länge 40 or SK L/40 for short. Schnellladekanone means quick loading cannon and referred not only to the speed which the horizontal sliding breech could be loaded by also by implication how fast it could be fired- up to fifteen rounds per minute with a well trained crew. Länge 40 refers to the length of the barrel in multiples of the calibre. The calibre of the gun was 10.5cm or roughly 4.1" (as the gun was often referred to in British texts measuring in inches).

The SK L/40 guns themselves weighed a massive 1,555kg, were 4.475 metres long and fired a 17.4kg high explosive shell with a muzzle velocity of 690 metres per second up to a maximum range of 12,200 metres (or almost eight miles). This out ranged the guns of the HMS Pegasus or for that matter any British naval gun off the East African coast, any Belgian gun on the Lake Tanganyika coast and for a while any land gun the allies had to oppose the Germans with.

The SMS Königsberg had ten of these guns, each of the guns were mounted on a fixed pivot stand, bolted to the deck of the ship. The type of stand used on the Königsberg was the naval Mittel-Pivot-Lafette C04.,

The stand was bolted to the deck of the ship and did not move. On top of the stand was the gun bucket which could rotate traversely. The gun bucket held the gun cradle via two trunion posts. The cradle could then pivot up and down within the gun bucket. On top of the cradle was a maintenance panel hatch to access the barrel. The barrel itself was held inside the cradle and could slide back within it to take the shock of firing.

Diagram of the Guns Mounting Parts and Recoil Mechanism of the 10.5cm SK L/40
Diagram by Bob Wagner

Similar 10.5cm guns had been used on German naval ships since around 1900. The 1905 modification was to add a more effective recoil system in the from of two damper cylinders below the barrel.

Whereas older naval guns rolled back on wheels or rails when they fired, the barrel of the SK L/40 recoiled back in its cradle, while the dampers took the force and returned the gun into position for its next round. This system saved time in re-aiming the gun and of course meant that it was ready for its next round almost immediately.

Gun Crew of the SMS Hertha, c1874-77
The crew are manually hauling a pre-recoil gun on rails back into position after firing.
Photo by Gustav Adolf Riemer by © Frankfurt University Koloniales Bildarchiv

The 10.5cm SK L/40 guns with the 1905 recoil dampers below were standard on many German cruisers from that date including the SMS Emden (which raided allied shipping in the Indian Ocean and bombarded Madras in British India during the First World War), the SMS Breslau (which along with the SMS Goeben caused the Turkish Ottoman Empire to join the First World War by bombarding the Russian Black Sea port of Sevastopol while under the Turkish flag) and of course the sister ships of the SMS Königsberg, the SMS Stettin, SMS Stuttgart and SMS Nürnberg (which sank with heavy loss of life at the Battle of the Falklands in 1914).

The gun in a slightly redesigned form as the longer 10.5cm SK40 L/45 was still in use on submarines and as naval anti-aircraft weapons in the Second World War.

Aside from the remaining guns from the SMS Königsberg which are our specific topic of interest, two other 10.5cm SK L/40 guns are still in existence from the SMS Emden and are on display in Australia, one at the Australian War Memorial Museum in Canberra and the other at Hyde Park, Sydney. These guns are identical 1905 models to those used on the SMS Königsberg.

Gun Crew
The gun crew would usually consist of five: A gun commander, to relay the orders for firing and oversee the gun crew, a gun layer who stood to the left to aim the gun, a gunner on the right to open a close the breech and also to fire the gun and two loaders. One loader took the shells from their cordite cases and passed them to the other who inserted them into the breech as the right side gunner opened it.

10.5cm Königsberg Midship Turreted Gun and Crew, pre-war

Operation and Aiming of the Gun onboard Ship
When the ship's officers on the bridge spotted a target, the target's coordinates or 'firing data' (degrees of elevation and traverse) were relayed to the gun crews. Elevation was based on the range of the target. Traverse was based on the direction of the target dependant on the bearing of the ship in relation to magnetic north. Adjustments were made to compensate for wind speed and for the speed of both the ship and its target and their relative directions from each other. The range of the guns was about 7.5 miles, so targets would usually be within eyesight of the officers and their gun crews up on deck on a clear day.

The gunners then set the gun to aim at the given coordinates. The gunner on the left set the set the traverse with a brass wheel attached to a toothed gearing system which pivoted the gun bucket around on its stand.

10.5cm SMS Emden Gun in Sydney, 2012
Note the traverse mechanism being a wheel handle on the right of the photo turning an axle which drives a gearing system on the teeth of the pivot stand.
Photo by Saberwyn at WikiCommons, Hyde Park Sydney 2012

Range via elevation was also set by means of a brass wheel on the left attached to a toothed gearing system which raised (by up to 20 degrees) or lowered (by up to 10 degrees) the barrel within the gun bucket. The degrees of traverse and elevation were marked on the pivot stand and elevation mechanism so a spotter could call degrees of aimed fire and the gun crew could modify their aim accordingly without themselves needing to see the target.

At the same time, the gun layer sighted the target if possible using the aiming sight on the left and made further adjustments to the traverse, the handle for which he could operate from the left sighting position. A second sight on the right of the barrel could be used to call further adjustments to the elevation. Both sights could be adjusted horizontally to allow for the elevation of the barrel.

Breech of a 10.5cm SK L/40 from the SMS Emden Australian War Memorial Museum
The two aiming sights can be seen here and the brass wheel to adjust the elevation via the toothed gearing system above it. Note also the degrees of traverse measured on the pivot stand and the recoil damper cylinder below the barrel. Several parts are missing from this gun, notably the breech block, traverse mechanism and pistol grip.
Photo by Andrew from Melbourne on the Ship Model Forum taken at the Australian War Memorial Museum, Canberra

Firing the Gun
The gun was fired either by a gunner to the right pulling a lanyard attached to the firing mechanism on the breech or by the gun layer on the left using a pistol grip.

Breech of another 10.5cm SK L/40 from the SMS Emden
This gun had different parts of the left side aiming and firing apparatus intact and missing. On this example the elevation wheel is missing but the traverse wheel and trigger grip are intact.
Photo at Hyde Park Sydney 2012

As the gun fired the barrel recoiled back inside the cradle which remained fixed. The shock of the recoil was taken by the 1905 two damper cylinders below the barrel on either side. These returned the gun to position for firing the next round.

Re-Loading the Gun
After firing, the gunner to the right, pulled the breech lever backwards and down to open the horizontal sliding breech, which also ejected the spent shell casing. A loader pushed a new shell into the breech and the right side gunner pulled the breech lever up to close the breech ready for firing a again. In trails, fifteen rounds per minute could be fired this way,

Opening and Closing the Breech Block

Breech open for loading with the handle rotated back and the sliding breech block slid out on the right	Breech closed for firing with the handle pushed forward and the sliding breech block slid inside the breech

10.5cm Gun Crew on Board the SS Goetzen on Lake Tanganyika
This posed photograph shows very well the actions of the crew. The gun layer is looking through the left aiming sight. the gunner to the left adjusts the traverse wheel out of sight behind the breech. The right side gunner controls the sliding breech block. One loader is pulling a shell from its case while the other prepares to load a shell into the breech.
Photo from WikiCommons

Turrets

10.5cm SK L/40 from the SMS Emden on display in its Turret
Photo by Andrew from Melbourne on the Ship Model Forum taken at the Australian War Memorial Museum, Canberra

Six of the guns on the SMS Königsberg were mounted in open backed armoured steel turrets that were bolted to plates which in turn were bolted to the gun cradle and revolved with them.  The turrets had a hole on either side for the aiming sights, the main one on the left (from the firers' point of view) being larger than the vertical slit on the right for elevation.

The guns that were turreted had a steel flange on the barrel cradle onto which was bolted a heavy steel shield which fitted into the firing slot in the gun's turret, protecting the gunners inside. Even when the guns fought later on land or were on display as allied trophies with their turrets long since discarded, the guns that had originally been installed in turret mountings on the SMS Königsberg can told from those that were in cupolas without turrets by the presence or absence of these flanges on the barrel cradle.

This was a turning point in our identification of different guns from each other and was spotted by Bob Wagner. Using this method we were able to see from period and more recent photographs that the guns captured at Kahe, Bagamoyo, Korogwe, Tabora and Masasi were from turreted guns, while those captured at Mwanza, the Ruvu River and Kibata were from the ship's side cupolas. (The guns put out of action at Kondoa-Irangi and Mahiwa had not at this stage been identified in photographic records.)

The buckets of the turreted guns can also be identified by bolt holes to hold the turret supporting plate. Gun buckets of guns with no turret have no bolt holes.

The turreted guns were the two on the fore deck, the two amidships and the two on the aft deck (marked on the diagram below in red). The four guns marked in blue on the sides fore and aft were not given turrets but had an unarmoured, detachable cupola around them.

Diagram of the Gun Configuration on the SMS Königsberg
Illustration published by Jane's 1914 from Wikimedia

The armoured turrets were retained by these six guns in 1915 after their salvage from the wreck of the Königsberg in their new static positions. Two of the turreted guns were in Dar Es Salaam, two were in Tanga, one was at the at the Elephant's Foot in Kigoma and the other was on board the SS Goetzen on lake Tanganyika. The turrets were discarded in 1916 when the guns were mounted on carriages for mobile warfare.

Closerlook at the Port Side of the SMS Königsberg
Note the two forward deck gun turrets and the fore port side cupola gun. In this image the cupola is opened to see the unturreted gun on its pivot stand. Incidentally, it was these port side guns that first opened fire on the SMS Pegasus at Zanzibar on 20 September 1914.
Photo by Walther Dobbertin from the Bundesarchiv on Wikimedia

Sources and Links
Reminiscences of East Africa' by Paul von Lettow-Vorbeck, Naval & Military Press Ltd 2004
'Königsberg- A German East African Raider' by Kevin Patience, Zanzibar Publications, Bahrain 1997
"Das Offizierskorps der Schutztruppe für Deutsch-Ostafrika im Weltkrieg 1914-1918" by Wolfgang-Eisenhardt Maillard and Jürgen Schröder, Walsrode 2003
"The First World War in Africa" by Hew Strachan, Oxford University Press 2004
Original Map from 'A Short History of the Great War' by AF Pollard, Methuen & Co, London 1920
'A Machine Gunner’s Odyssey Trough German East Africa: January 1916- February 1917'  by ES Thompson, South African Military History Journal
Australian War Memorial Museum in Canberra
Photos by Andrew from Melbourne on the Ship Model Forum
NavWeaps
Lovett Artillery
Axis History Forum Discussion on the SMS Königsberg Guns in English
Panzer Archiv Forum Discussion on the SMS Königsberg Guns in German