The Formidable Tsetse

As the U-boats became more heavily armed against air attack, so the RAF sought to find effective countermeasures. Illustrative of a new menace posed to U-boats during 1943 was the introduction of the Tsetse Mosquito by the RAF.

This was a Mosquito Mk XVIII uniquely fitted with a formidable 57 mm ‘Molins’ anti-shipping gun with only 18 of this type being constructed. The huge six-pounder gun replaced the 20 mm cannons usually fitted, although the Mk XVIII retained its battery of four x .303 Browning machine guns. These served a dual purpose: to assist the pilot in his aim of the main weapon and to keep the heads down of any would-be anti-aircraft gunners during the run-in to target. Only 25 x rounds of 57 mm ammunition were carried.

One of the problems with the gun was that it required a long steady attack run, starting from an altitude of 5,000 ft and diving at 30 until within range. This left the Mosquito vulnerable to Flak. However, on 7 November 1943, a Tsetse Mosquito of 618 Squadron, flown by Flying Officer A J L Bonnett, RCAF, carried out the first such attack* on U-123.

Firing eight rounds, Bonnet achieved several hits on U-123’s conning tower and hull, rendering it unable to dive because of an 18 x 6.5 cm hole (7.1 x 2.6 inch) hole in the boat’s pressure hull. One crew member, Bootsmaat Günther Struve, was killed and two others were wounded in what had been a very accurate attack.

The U-123, a Type IXB, had previously ‘starred’ in the German propaganda film U-boote westwärts! (U-boats Westwards!) of 1941 which told a fictitious tale of the adventures of a U-boat and her crew.

Prior to the Tsetse Mosquito attack, she had been depth-charged and damaged off Cap Finisterre by Allied vessels on or around 25 August 1943.

On 19 August 1944 she was scuttled at Lorient, but later raised by the French and going on to serve in the French Navy as Blaison (Q165) until being decommissioned in August 1959.

■ An RAF corporal shows off the 57 mm shell carried by the Tsetse Mosquito – a formidable anti U-boat weapon.

■ Crew members man the 20 mm Flak gun on the conning tower of U-123. This is a posed shot and a still from the 1941 propaganda film U-boote westwärts! The low angle of elevation on the gun reflects the low-level nature of Allied aircraft attacks against U-boats. In fact, the U-123 was badly damaged by a Tsetse Mosquito on 7 November 1943 when several holes were punched in the conning tower and hull by 57 mm shells.