Perhaps the world’s most recognizable sword, thanks to Hollywood and TV, the katana is a single-edged curved sword, with a long handle for two-handed use that features a square or circular guard, and a slender blade usually measuring two and a half feet in length. They are among the finest cutting weapons in history, and were used by Japanese samurai since feudal times, with the earliest recorded mention in the historic record dating to the 12th century.
Katanas are the product of natural evolution, having started off as hefty “great swords” that grew thinner, lighter, and more agile over time in order to meet the demands of emerging combat styles that were increasingly reliant upon speed. They became popular with samurai because the ease and speed with which they could be drawn was a decided asset for the newer and faster-fighting styles, collectively dubbed kenjutsu, the art of sword fighting, in which the issue was often settled within seconds, and speed of reaction spelled the difference between life and death.
Katanas, coupled with a smaller sword, were thrust, sharp edge facing upwards, through the bearer’s obi – a sash wrapped tightly around the samurai’s waist – in a configuration known as daisho that identified the wearer as a samurai, and only members of that class were authorized to tote paired swords in that fashion. Wearing the katana in the daisho style facilitated a speedy draw, ideally allowing the samurai to draw and cut down his opponent in a single fluid motion, and an entire martial art, Iaido, was dedicated to the speedy retrieval of the katana from its scabbard.
Katanas are made from tamahagane steel, which is produced by traditional Japanese smelting processes that result in layered steels with varying carbon concentrations, that are welded, folded, and hammered out to reduce impurities. A katana needs a sharp and hard edge, but steel that is hard enough for a sharp edge is brittle, while softer steel that is not brittle will not take and retain a sharp edge. Katana makers solved the dilemma by using four metal bars: a soft iron bar to guard against breaking, sandwiched by two hard iron bars to prevent bending, and rounded off with a steel bar to take the cutting edge.
The four bars were heated at high temperature, then hammered into a long bar that would become the blade. Contrary to myth, samurai blades were not folded thousands or even hundreds of times – that much folding would be counterproductive and render the steel useless for a sword. When the sword was sharpened, the steel took a razor-sharp edge, while the softer iron prevented the blade from breaking. Well-crafted katanas became prized heirlooms, passed down generations of samurai families for centuries, and magnificent specimens of centuries-old katanas can be seen in the Tokugawa Art Museum in Nagoya, Japan.