German submarine U-47 was a Type VIIB U-boat of Nazi Germany's Kriegsmarine during World War II.

[1] She was laid down on 25 February 1937 at Friedrich Krupp Germaniawerft in Kiel as yard number 582 and went into service on 17 December 1938 under the command of Günther Prien.

During U-47's career, she sank a total of 31 enemy vessels, including the British battleship HMS Royal Oak, and damaged nine more.

On 3 September, war was declared and U-47 received orders to initiate hostilities against British ships, but none were encountered on the first day.

[7] Just after dawn on 5 September, Engelbert Endrass – serving as first watch officer aboard U-47 – spotted SS Bosnia zigzagging and in a darkened state.

Prien surfaced and fired a single shot from his 88 mm deck gun to stop the ship but instead Bosnia made steam and began radioing an alert ('SSS') along with its name and position.

While the Rio Carlo did stop moving, it nonetheless broadcast the submarine alert, prompting Prien to fire an ineffective warning shot.

A further three shots from the deck gun were fired onto the bridge of Rio Carlo, upon which the broadcast ceased and the crew abandoned ship.

It began to make steam after its crew departed and Prien was forced to take emergency measures to avoid the vessel.

He returned to Gartavon and attempted to finish her as he had his previous victims, but the torpedo malfunctioned and Prien instead used the deck gun to wreck the ship and sink its cargo of iron ore.[7] During this first patrol, which ended with her arrival in Kiel on 15 September 1939, three vessels were sunk for a total of 8,270 GRT.

On 14 October 1939 (six days after leaving port), she succeeded in penetrating the Royal Navy's primary base at Scapa Flow.

After reloading the bow tubes the last salvo of three torpedoes struck the British warship, causing severe flooding.

Two other U-47 crew members also earned the Knight's Cross later on during World War II: the chief engineer (Leitender Ingenieur) Johann-Friedrich Wessels and 1st watch officer (I. Wachoffizier) Engelbert Endrass.

[citation needed] Many years later, in September 2002, one of the unexploded torpedoes that U-47 had fired during the attack on Royal Oak rose to the surface from its resting place on the bottom.

The unexploded torpedo, minus its warhead, gradually drifted towards the shore, where it was spotted by a crewman aboard the Norwegian tanker Petrotrym.

A Royal Navy tugboat intercepted the torpedo, and after identifying it as having belonged to U-47 63 years earlier, EOD (explosive ordnance disposal) personnel discarded it a mile from shore.

[citation needed] Following a lavish celebration in Berlin for the sinking of HMS Royal Oak in which the crew members of U-47 were received by Adolf Hitler and decorated, the boat returned to sea on 16 November 1939.

[11] Following the sinking of Navasota, British destroyers briefly fired depth charges at the U-boat but she managed to safely evade the attack without any damage.

Along with six other U-boats in Wolfpack Prien, she attacked Convoy HX 47 and sank the British SS Balmoralwood on 14 June.

Within less than a month, the boat sank a further seven vessels, San Fernando on the 21st, Cathrine on the 24th, Lenda and Leticia on the 27th, Empire Toucan on the 29th, Georgios Kyriakides on the 30th, and SS Arandora Star on 2 July.

[16] U-47 left her home port of Lorient on 3 November 1940 and moved out into the North Atlantic in search of Allied convoys.