8 June 1943

8 June 1943 Channel Islands Sea Defence diary

Weather: wind 270°, 4 m/sec. On the basis of Luftwaffe radar plots north-west of Guernsey, the Sea Commander ordered a naval-target alarm for all coastal batteries.

From 02:08 to 02:37, enemy naval targets north-west of Guernsey, at ranges of 150–276 hectometres, were engaged by Batteries Steinbruch and Mirus. No hits were observed and the enemy did not return fire.

At Batterie Mirus, the lugs on the horn rings sheared off during the third round of No. 3 gun and the second round of No. 4 gun, at barrel lives of 99 and 101 rounds respectively. Both guns became temporarily unfit for combat. The brake cylinders and compressed-air systems had been filled correctly. Krupp fitters repairing No. 1 gun considered the failures a design defect. High-explosive shells were fired, each with two 71-kilogram charges, at 31° elevation.

Ammunition expenditure: Batterie Steinbruch, 30 high-explosive shells with nose fuze and cap, L 4.6, and seven of the same with illuminating cases; Batterie Mirus, nine high-explosive shells L 3.8. The source prints “cm” after these L designations; these are reproduced as projectile designations, not stated as the gun calibres.

All Guernsey coastal batteries were alerted. Fire was initially withheld in the expectation that the targets would enter a more favourable range. The targets lay outside Army Coastal Artillery Battalion 452's sector and at the edge of that of Army Coastal Artillery Battalion 727. At first only Batterie Steinbruch was to engage; when the targets failed to close, permission to fire was given at 01:55 to Batterie Steinbruch and Army Coastal Battery 461.

Batterie Steinbruch’s surprise fire of three salvos caused the targets to turn to port and withdraw northwards at high speed. Army Coast Battery 461 did not fire because communications with the radar station failed. Batterie Mirus fired three salvos at the retreating enemy. The targets passed immediately west of the Casquets and continued northwards. The Alderney batteries were alerted and ready, but neither Luftwaffe nor naval radar there detected the targets, so no fire was opened.

From their speed and radar contacts, the vessels were judged to be motor torpedo boats or torpedo boats, possibly laying mines on Routes Ida or Herz, where new mines had been found east of Sark, or preparing a commando raid on one of the islands.

The communications failure which prevented Army Coastal Batteries 461 and 472 from firing was considered regrettable, and an investigation was ordered.

The plots came almost entirely from the Luftwaffe radar station Adlerschloß. The naval radar set Marchant detected the targets only from 01:48 to 01:59; the Alderney naval radar set detected nothing. The range of the naval radar equipment was inadequate. Without the Luftwaffe plots no engagement would have been possible, and the enemy could have laid mines or landed commandos without hindrance.

One gun of Army Coastal Battery 465 was expected to be unavailable for approximately eight days while its support plate was replaced. At 14:25, the 319th Infantry Division ordered Alert Level I.

Undated subsequent assessment by the Admiral Channel Coast concerning the 8 June entry: the Sea Commander’s comments were endorsed. Reference was also made to the Admiral Channel Coast’s own war diary for 8 June 1943 at 08:00. Signed by the Chief of Staff for the Commanding Admiral; signature unclear. Naval Staff registry 1684/43.

T-1022 Roll 2422, scans 0652–0653, 0656.