Naval combat underwent a significant metamorphosis during World War II. Nazi Germany and Imperial Japan launched some of the most powerful battleships ever to sail the world's oceans, yet the conflict witnessed the emergence and triumph of the aircraft carrier as the 20th century's true monarch of the seas. Submarine warfare expanded and developed, while aircraft technology and doctrine experienced several revolutionary changes due to the unforgiving demands of the new combat environment. 

While many large-scale naval engagements were fought in the Pacific at places like the Coral Sea, Midway, and the Philippines, engagements were rare in Europe. There were flurries of action as the German warships Admiral Graf Spee and Bismarck were hunted and destroyed in 1939 and 1941, and there was a constant battle between surface ships and German U-Boats that lasted throughout the war. But there was only one major naval engagement fought between battle fleets in Europe – at the Battle of Cape Matapan, the British Royal Navy and the Royal Australian Navy would square off with the Italian Regia Marina in early 1941.

Though it was the most decisive naval battle in the Mediterranean, the Battle of Cape Matapan has largely been forgotten today, even as military historians have recognized its significance and some have even compared it with the legendary Battle of Trafalgar in 1805. Indeed, the battle shaped the remainder of the war in the Mediterranean, which would prove crucial when the Western Allies would use it to amphibiously invade Sicily in 1943, marking their return to the European continent.