Steel

“What is steel compared to the hand that wields it?” — Thulsa Doom (fictional, but the question is ancient)

Steel — iron refined to precise carbon content — combined strength, flexibility, and durability in a single material. Mass-produced steel built the railways, the skyscrapers, the warships, and the bridges of the modern world.

Unlocks

• Units: Battleship

Historical Background

Steel has been produced in small quantities since antiquity — Indian wootz steel and Damascus steel were prized for their quality — but mass production was impossible until the mid-19th century. Henry Bessemer’s converter (1856) blew air through molten pig iron to burn off excess carbon, producing steel cheaply and in vast quantities for the first time. The Siemens-Martin open-hearth process, developed shortly after, offered even greater control over the final product’s composition.

The effects were transformative. Steel rails replaced brittle iron, enabling heavier trains and faster speeds. Steel-framed buildings rose to previously impossible heights — the skyscraper was born. And at sea, steel revolutionised naval warfare. The ironclad warships of the American Civil War gave way to all-steel battleships: massive, heavily armoured vessels mounting enormous rifled guns. HMS Dreadnought (1906) rendered every existing battleship obsolete overnight, triggering a naval arms race that shaped the geopolitics of the early 20th century. The battleship remained the symbol of national power until aircraft carriers supplanted it during the Second World War.