Inside the Geobukseon: The Korean Warship That Beat 133 Japanese Ships With Just 13 (Full Process)

Step inside a 16th-century Korean shipyard and discover how a wooden warship armored with iron plates, ringed with iron spikes, and topped with a dragon-headed bow that belched smoke and cannon fire — designed by a single naval commander who had been demoted, imprisoned, tortured, and reinstated — became the weapon that stopped the Japanese invasion of Korea and preserved a nation of eight million people in one of the most improbable naval victories in human history. This full-process historical documentary explores the engineering, the desperate strategy, and the world-changing naval campaign of the Geobukseon — the Korean "Turtle Ship" designed by Admiral Yi Sun-sin during the Imjin War of 1592-1598. Built from Korean pine and oak, plated with iron across its upper deck, ringed with iron spikes to prevent boarding, mounted with a dragon head at the prow that fired cannons through its mouth, and armed with 11 cannon ports on each side firing four types of Korean naval guns — the cheonja, jija, hyeonja, and hwangja chongtong — the Geobukseon was one of the most advanced warships in the world at the end of the 16th century. Explore every major stage of Geobukseon construction and the naval campaigns of Admiral Yi Sun-sin, including: Selecting and seasoning Korean pine and oak for the hull and iron-plated deck Constructing the enclosed curved deck in the shape of a turtle shell Riveting iron plates across the upper deck to deflect Japanese arquebus fire Fitting iron spikes across the roof to prevent samurai from boarding Mounting the dragon head at the prow to fire cannons and release smoke screens Installing 11 cannon ports on each side for cheonjachongtong and hyeonjachongtong guns Deploying the Geobukseon alongside the panokseon fleet against Japanese warships Blending Joseon-era Korean metallurgy, the naval tactics of one of history's greatest admirals, and the desperate war for the survival of a nation, this video reveals how a single warship design became the shield of Korea against a Japanese invasion led by the unifier of Japan, Toyotomi Hideyoshi. In April 1592, Hideyoshi launched over 158,000 soldiers and 700 ships against Korea, intending to conquer Korea and then invade Ming China. The Korean army collapsed within weeks. Seoul fell in three weeks. Pyongyang fell soon after. But the Korean navy, commanded by Admiral Yi Sun-sin from his base in the southwestern archipelago, held. In battle after battle — Okpo, Sacheon, Hansando, Angolpo, Busan — Yi's fleet of panokseons and Geobukseons cut off the Japanese supply lines by sea and destroyed hundreds of Japanese warships without losing a single ship of his own. Then, in 1597, the second Japanese invasion began. King Seonjo, misled by Japanese intelligence and Korean court factions, demoted and imprisoned Admiral Yi. Yi was tortured and stripped of his rank. The new Korean naval commander, Won Gyun, lost 156 of the 169 Korean warships at the disastrous Battle of Chilcheollyang in August 1597. Only 13 ships remained. In desperation, King Seonjo reinstated Yi. Yi took command of the 13 surviving warships and, on October 26, 1597, at the Battle of Myeongnyang, he faced a Japanese fleet of approximately 133 warships in the narrow strait of Uldolmok. Using the strait's ferocious tidal current, an iron chain barrier, and the terrifying combination of ironclad Geobukseons and traditional panokseons, Yi's 13 ships destroyed 31 Japanese ships and killed the Japanese admiral Kurushima Michifusa. Zero Korean ships were lost. The Japanese naval advance was broken. Fifteen months later, on December 16, 1598, at the Battle of Noryang, Yi Sun-sin was struck by a Japanese musket ball as the combined Korean-Ming Chinese fleet destroyed the retreating Japanese armada. His final order to his officers, as he lay dying on the deck of his flagship: "The battle is at its height. Do not announce my death." Admiral Yi Sun-sin died undefeated in 23 naval battles. Modern historians rank him among the greatest naval commanders in world history — alongside Nelson, Themistocles, and Nimitz. If you enjoy Korean history documentaries, Admiral Yi Sun-sin, the Imjin War, naval engineering, or full-process explorations of historical warship technology, this cinematic walkthrough reveals how a single iron-plated warship saved a nation of eight million people from conquest. 🔔 Subscribe to The Archaic Method for more Inside documentaries exploring ancient workshops, maritime engineering, and the full processes behind the warships that changed history.