'Prien' (i) was a U-boat wolfpack operation of the 'second wave' in the Atlantic against the HX.47 and HX.48 convoys (12/17 June 1940).

Named for Oberleutnant Günther Prien, commander of U-47, this wolfpack comprised U-25, U-28, U-30, U-32, U-38, U-47 and U-51.

On 20 June U-51 attacked the HGF.34 convoy without success. On 21/22 June U-30, U-32 and U-47 tackled the HX.49 convoy, U-47 sinking the 13,056-ton British tanker San Fernando, Oberleutnant Hans Jenisch’s U-32 the 9,026-ton Norwegian tanker Eli Knudsen and Kapitänleutnant Fritz-Julius Lemp’s U-30 the 3,999-ton Norwegian vessel Randsfjord; U-30 then departed to Ferrol in Spain, where the boat took on fresh supplies to extend its patrol into July.

In separate operations Kapitänleutnant Heinz Beduhn’s U-25 sank the 17,046-ton armed merchant cruiser Scotstoun on 13 June and damaged the 7,638-ton French tanker Brumaire on 19 June. Kapitänleutnant Günter Kuhnke’s U-28 sank the 2,417-ton Finnish Sarmatia and 3,443-ton Greek Adamandios Georgandis on 19 June, and two days later the 4,876-ton British Q-ship Prunella. On 20 June Lemp’s U-30 sank the 4,876-ton British Otterpool, on 28 June the 5,053-ton British Llanarth, then turned its attentions to the SL.36 convoy to sink the 5,218-ton British Beignon on 1 July and the 3,154-ton Egyptian Angele Mabro on 6 July before becoming, on 7 July, the first U-boat to arrive at the new base at Lorient in German-occupied France.

On 18 June Jenisch’s U-32 sank the 1,522-ton Norwegian Altair and 108-ton Spanish trawlers Sálvora and Faro-Ons, and on 19 June the 5,334-ton Yugoslav Labude. On 14 June Kapitänleutnant Heinrich Liebe’s U-38 sank the 9,973-ton Norwegian tanker Italia, 2,238-ton Canadian Erik Boye, 5,403-ton Greek Mount Myrto, on the following day the 1,776-ton Swedish Tilia Gorthon, on 21 June the 5,809-ton Belgian Luxembourg and on 22 June the 5,154-ton Greek Neion. On 14 June Prien’s U-47 sank the 5,834-ton British Balmoralwood, on 24 June the 1,885-ton Panamanian Cathrine, on 27 June the 4,005-ton Norwegian Lenda and 2,580-ton Dutch tanker Leticia, on 29 June the 4,127-ton British Empire Toucan, on 30 June the 4,201-ton Greek Georgios Kyriakides and finally, on 2 July, the 15,501-ton British troopship Arandora Star carrying German and Italian civilians to internment in Canada.

On 25 June Kapitänleutnant Dietrick Knorr’s U-51 sank the 5,395-ton British Windsorwood and 12,049-ton British tanker Saranac, and on 29 June the 4,724-ton British Q-ship Edgehill.