The First Happy Time was a phase of the Battle of the Atlantic during which German Navy U-boats enjoyed significant success against the British Royal Navy and its allies. It started in July 1940, almost immediately after France was conquered by Germany, bringing the German U-boat fleet closer to the British shipping lanes in the Atlantic; and it ended in April, 1941. 

U-47's sixth patrol under the Gunter Prien Commander on 6th July 1940 (Courtesy of U-historia)

U-47's ninth patrol under the Gunter Prien Commander on 3rd November 1940 (Courtesy of U-historia)

U-47's tenth patrol under the Gunter Prien Commander on 20th February 1941 (Courtesy of U-historia)

The reason for this successful German period was the British lack of radar and Huff-Duff equipped ships which meant that the U-boats were very hard to detect when they made nighttime surface attacks (ASDIC [sonar] could only detect submerged U-boats).

Kretschmer with the crew of U-99 celebrating his Knight's Cross award on 8 August 1940 (Deutsches Bundesarchiv - Bild 101II-MW-0951-24A)

Kapitänleutnant Otto Kretschmer, 14 November 1940 (Deutsches Bundesarchiv - Bild 183-L16644)

Admiral Erich Raeder presents the Knight's Cross to Otto Kretschmer (a U-boat "ace") in August 1940. Later in November, Oak Leaves were added to the award when he reached 200,000 tons of tonnage sunk (Courtesy of U-historia)

These U-boat operations from the French bases were spectacularly successful. U-boat crews became heroes in Germany. From July 1940 to the end of October, 282 Allied ships were sunk off the north-west approaches to Ireland for a loss of 1,489,795 tons of merchant shipping.

German U-Boot U-100 on final approach to the German base at Lorient, France in Sept 1940. While nobody looks too concerned about a visit from the British, note that the lookout is keeping a sharp eye to the north - and England (Courtesy of World War II in Pictures)

Schepke’s last command, U-100, was damaged by depth charges from HMS Walker and HMS Vanoc while attacking a convoy in the North Atlantic (Courtesy of World War II in Pictures)

In the forenoon of the 07th of November 1940 "U-100" departed Lorient for its 4th combat patrol Courtesy of Deutsches U-Boot-Museum)

This was the heyday of the great U-boat aces like Günther Prien of U-47, Otto Kretschmer (U-99), Joachim Schepke (U-100), Engelbert Endrass (U-46), Victor Oehrn (U-37) and Heinrich Bleichrodt (U-48).

Endrass (foreground) and crew members, 1940 (Deutsches Bundesarchiv - Bild 183-L15633)

(Courtesy of U-historia)

U-46 under Kptlt. Endrass returning from patrol. He did not quite make these lists though (Courtesy of uboat.net)

Kptlt. Oehrn amidst the crew of U-37 (Courtesy of uboat.net)

U-37 in Lorient, 1940 (Deutsches Bundesarchiv - Bild 101-IIMW103211)

U-37 in Wilhelmshaven, 1940 (Deutsches Bundesarchiv - Bild 101-IIMW561330A)

One of the main reasons for the end of the First Happy Time is because in March 1941, Germans lose three prominent U-boat aces: Günther Prien (MIA), Joachim Schepke (KIA) and Otto Kretschmer (POW).

The U-48 Commander Heinrich Bleichrodt back to their base in Lorient, on September 25, 1940, after a successful mission (Courtesy of 24th Flotilla "Geweih")