alternatehistory.com

http://uboat.net/articles/?article=23

When the British Expeditionary Force (BEF) finally set out for Narvik on April 15th, Naval High Command and BdU had a difference of opinions as to where exactly the British will disembark. High Command considered the fjords Lavangen and Gratengen to the north of Narvik most probable. Dönitz, however, believed that the site of disembarkation would be Bygdenfjord, also to the north of Narvik, but at a greater distance. Consequently, he was proven right when late on April 15 Gunther Prien of U-47 arrived at Bydgenfjord and spotted three large British transports (some 30,000 GRT each) and several smaller ones disembarking troops in fishing boats. Immediately the Raging Bull fired 8 torpedoes with impact pistols at the stationary and overlapping targets, but all of them missed. This could have been a major disaster for the BEF and a valuable help for the outnumbered mountain troops defending Narvik.

These failed because of a manufacturing defect that caused the torpedoes to run too deep, causing them to miss. What if these 8 torpedoes hit their mark? It would mean over 100k GRT of shipping gone in a matter of minutes, the loss of thousands of British troops, and a dislocation of the Allied effort around Narvik.
What happens then during the Norwegian campaign? Does it provoke the British to reassess their naval doctrine? What about the Germans and the torpedo crisis? Do they still tackle the issue around the same time?
Top