The German submarine U-47, commanded by Kapitänleutnant Günther Prien, executed a daring and successful operation against the British battleship HMS Royal Oak in the harbor of Scapa Flow, Scotland. This strategic location served as the main base of the Royal Navy's home fleet and was expected to be a secure area protected by underwater nets and naval defenses. However, in the early hours of October 14, 1939, U-47 managed to evade these defenses and fired torpedoes at the battleship. The Royal Oak was struck by multiple torpedoes, which caused significant destruction and led to its sinking within just minutes. The attack resulted in the loss of 833 crew members, marking one of the largest single losses of life for the Royal Navy during the war.

The U-47's success was a significant morale booster for Nazi Germany and highlighted the effectiveness of submarine warfare, particularly in the early stages of World War II. The loss of the Royal Oak forced the British Admiralty to reconsider their defense strategies and naval preparedness, establishing an urgent need for improved anti-submarine measures. This incident contributed to the perception and reality of the threats posed by U-boats in British waters, significantly impacting naval operations for the duration of the conflict.

The sinking of HMS Royal Oak exemplified how vulnerable even the most powerful battleships could be when faced with the tactics of modern submarine warfare. It was a pivotal moment that illustrated the changing nature of naval warfare, where traditional surface fleets had to adapt to counter the growing threat from submarines. Subsequently, the British focused heavily on anti-submarine tactics and technology, leading to the development of deeper and more complex naval strategies as the war unfolded.