An explosion, likely caused by a World War II–era naval mine, capsized the Soviet ship Novorossiysk in the harbor of Sevastopol, with the loss of 608 men.

A naval mine is a self-contained explosive weapon placed in water to damage or destroy surface ships or submarines. Similar to anti-personnel and other land mines, and unlike purpose launched naval depth charges, they are deposited and left to wait until, depending on their fuzing, they are triggered by the approach of or contact with any vessel.

Giulio Cesare was one of three Conte di Cavour-class dreadnought battleships built for the Royal Italian Navy in the 1910s. Completed in 1914, she was little used and saw no combat during the First World War. The ship supported operations during the Corfu Incident in 1923 and spent much of the rest of the decade in reserve. She was rebuilt between 1933 and 1937 with more powerful guns, additional armor and considerably more speed than before.

Sevastopol, sometimes written Sebastopol, is the largest city in Crimea and a major port on the Black Sea. Due to its strategic location and the navigability of the city's harbours, Sevastopol has been an important port and naval base throughout its history. Since the city's founding in 1783 it has been a major base for Russia's Black Sea Fleet. During the Cold War of the 20th century, it was a closed city. The total administrative area is 864 square kilometres (334 sq mi) and includes a significant amount of rural land. The urban population, largely concentrated around Sevastopol Bay, is 479,394, and the total population is 547,820.