HMS Nelson, a British battleship, was an important part of the Royal Navy during World War II. On December 4, 1939, while operating off the coast of Scotland, the ship struck a mine that had been laid by the German submarine U-31. The mine explosion caused considerable damage to the hull, necessitating a period of extensive repairs. The incident signified the increased peril that naval forces encountered from both surface and underwater threats as conflicts escalated in the Atlantic waters. Following the incident, HMS Nelson was decommissioned for repairs which lasted until August 1940.

The laying of mines was a strategic move employed by the German forces to disrupt Allied naval power during the early months of the war. U-31 was one of many submarines deployed by Germany in their campaign against Britain. Mines presented a constant hazard to naval operations, highlighting the vulnerability of major warships in contested waters. As a result, the Royal Navy had to address the growing threat from U-boats and mines by adapting its tactics and enhancing its naval defenses.

HMS Nelson, upon returning to service post-repair, continued to participate in various significant naval engagements. The incident underscored the unpredictability of naval warfare and set a precedent for the Royal Navy’s awareness of undersea threats. The battleship's eventual repairs also led to improvements in naval tactics that would influence future operations in the North Atlantic.