Salamis was a partially constructed capital ship, referred to as either a dreadnought battleship or battlecruiser, that was ordered for the Greek Navy from the AG Vulcan shipyard in Hamburg, Germany, in 1912. She was ordered as part of a Greek naval rearmament program meant to modernize the fleet, in response to Ottoman naval expansion after the Greco-Turkish War of 1897. Salamis and several other battleships—none of which were delivered to either navy—represented the culmination of a naval arms race between the two countries that had significant effects on the First Balkan War and World War I.

The dreadnought was the predominant type of battleship in the early 20th century. The first of the kind, the Royal Navy's HMS Dreadnought, had such an effect when launched in 1906 that similar battleships built after her were referred to as "dreadnoughts", and earlier battleships became known as pre-dreadnoughts. Her design had two revolutionary features: an "all-big-gun" armament scheme, with an unprecedented number of heavy-calibre guns, and steam turbine propulsion. As dreadnoughts became a crucial symbol of national power, the arrival of these new warships renewed the naval arms race between the United Kingdom and Germany. Dreadnought races sprang up around the world, including in South America, lasting up to the beginning of World War I. Successive designs increased rapidly in size and made use of improvements in armament, armour, and propulsion throughout the dreadnought era. Within five years, new battleships outclassed Dreadnought herself. These more powerful vessels were known as "super-dreadnoughts". Most of the original dreadnoughts were scrapped after the end of World War I under the terms of the Washington Naval Treaty, but many of the newer super-dreadnoughts continued serving throughout World War II.