Batterie Mirus
The Westbefestigungen (Inspector of Western Fortresses) was put in overall command, and reports would be made every two weeks of progress.
[2]: 197 This referred to the “permanent fortification” of the Channel Islands to make an impregnable fortress to be completed by December 1942.
[4]: 448 The plan had required that three batteries of 38 cm guns be based on the islands to also provide protection for the bay of Saint-Malo, but they could not be supplied.
It was at this conference that the proposal for the 30.5 cm Batterie Nina was approved, as four guns and 1,000 rounds of ammunition could be provided at short notice.
[1]: 13–14 The work would continue as planned, despite the death of Dr Todt, who was also Minister of Armaments, in a plane crash in February 1942.
The Obukhovskii 12"/52 Pattern 1907 gun barrels, which were 15.85 meters long, were cast at the Obuchov foundry in 1914 and became the main armament for one of a series of dreadnoughts of the Imperial Russian Navy's Black Sea Fleet.
This 1914 ship, had been surrendered by the White Fleet in 1921 and interned in Bizerta, where for non-payment of harbour dues she was sold for scrap in the late 1920s, although she was only broken up in 1936.
[1]: 20 The shells were propelled with cordite at up to 1,020m/sec, and a compressed air system was developed to allow for the barrels to be cleaned after each round.
Preparations for the transport in Guernsey included taking trees down with several junctions having walls demolished so that the convoy could avoid sharp corners.
Other workers included specialist experts brought to the island from Germany or occupied countries and Guernsey men.
[8]: 168 [9] If British aircraft were near, the Germans would cut all the lights at their building sites, but not the power to the concrete mixers.
[1]: 52 The three reserve ammunition bunkers, which were built above ground, were camouflaged as houses, given pitched roofs and painted windows and doors.
[7] The April demonstration was witnessed by several observers, including an official photographer, who stood too close and was thrown into a ditch by the concussion.
[1]: 50 Before test firing local house owners were warned to open windows to avoid the glass shattering.
[7] The command centre used a mechanical computer, which took into account details of wind speed, air pressure and firing range.
The control room was manned twenty-four hours a day and required a crew of 18 working shifts.
[1]: 80 Risk of damage was always a factor in deciding whether to fire, as was the limited life span of the barrels which would need to be returned to the factory to have the internal grooved bore replaced.
[1]: 19 Mirus was called into action on D-Day, attacking naval units patrolling off of the Cotentin peninsula, damaging two vessels from the resulting blast of a near miss from one 30.5 cm shell.
Thereafter, Allied ships were ordered to keep their distance, even so a number of incidents of destroyers coming too close resulted in a salvo being fired from Mirus.
[15]: 296 The Channel Island naval commander, Kommandant der Seeverteidigung Kanalinseln was created in June 1942, Kapitän-zur-See Julius Steinbach, was based at St Jacques in Guernsey, where a Naval command centre abbreviated to Seeko-Ki was built.
[16]: 73 The drive to recover scrap metal and a strong dislike of anything German in the islands saw the majority of the metalwork in the battery removed and scrapped from 1947 onwards, this included the armoured turrets, doors, hoists, engines, observation domes, ventilation duct, cabling etc.
[17]: 115 An ex-RAF Coles mobile crane was used to lift out depth charges found in the central pivots of the gun pits during the scrap metal drive of the early 1950s.
