[1] The auxiliary cruiser Pinguin/Schiff 33 (Kapitän Ernst-Felix Krüder), was originally the freighter Kandelfels, which had been launched in 1937 of 7,766 gross register tons, capable of 16 kn (30 km/h; 18 mph).

The prizes were sent to Occupied France where one was renamed Adjutant and was used as minelayer for the German raiders in the South Atlantic and the Indian Ocean.

[4] After sinking Clan Buchanan on 28 April, Pinguin sailed north-west and on 4 May, fuelled and provisioned Adjutant, which was sent away to wait at a rendezvous near the Saya de Malha Bank.

Just after 5:00 a.m. on 7 May, Pinguin intercepted and sank the 3,663 long tons (3,722 t) tanker British Emperor, which was on passage from Durban to Abadan, about 375 nmi (694 km; 432 mi) east-south-east of Cape Guardafui.

HMS Glasgow, steaming from the Gulf of Aden, passed Cape Guardafui that morning at 23 kn (43 km/h; 26 mph), to a position about 100 nmi (190 km; 120 mi) south-east of the headland.

Farther west, the armed merchant cruiser HMS Hector, patrolled from the Equator to a position 300 nmi (560 km; 350 mi) to the south-west.

[7] On the afternoon of 7 May, the two aircraft on Cornwall flew reconnaissance sorties for three hours and then altered course to get on the line of the main Vignot search.

The OIC tracked raiders, based on the position of the sinking of Allied merchant ships and by collating rare sightings and distress signals.

From May to November 1941, the Germans lost Pinguin and two more commerce raiders but Enigma decrypts by the Government Code and Cypher School (GC&CS) were only involved in one sinking.

[12] German commerce-raiders used the Heimische Gewässer (Home Waters) Enigma settings, known as Dolphin to the British, before departing and when returning to Germany.

When at sea, Enigma-equipped raiders used the Ausserheimisch settings if they broke radio silence, which Hut 4 at Bletchley Park never managed to penetrate.

Atlantis, the third raider lost in 1941, was sunk by HMS Devonshire on 22 November after the British read U-boat signals in the Heimische Gewässer setting, introduced in October 1941, to arrange a fuelling rendezvous.