Admiral Edward Vernon's expedition of 186 ships and roughly 27,000 men — one of the largest amphibious forces assembled before the 20th century — failed to take Cartagena de Indias from a vastly outnumbered Spanish garrison under Blas de Lezo. Yellow fever and dysentery killed far more attackers than combat did. The British withdrawal marked a humiliating setback in the War of Jenkins' Ear and a defining Spanish colonial triumph.
Blas de Lezo, the one-eyed, one-armed, one-legged Spanish admiral, commanded fewer than 3,000 men and six ships against an armada nearly ten times its size. He had lost the limbs in earlier campaigns and was nicknamed 'Half-Man' by his own sailors, yet he organized Cartagena's harbor defenses with such cunning — sinking ships to block channels, fortifying key forts — that Vernon's assault stalled for weeks.
Disease proved the decisive weapon. Tropical fevers swept through British ranks crowded aboard ships in the harbor, killing thousands before a shot was fired in the final assault. When British troops finally stormed the fort of San Felipe de Barajas in April, poor scaling ladders and fierce resistance turned the attack into a slaughter.
By May 4, Vernon ordered the remnants of his fleet to withdraw, having lost an estimated 18,000 men to disease and combat — one of the costliest defeats in British military history. Vernon had been so confident of victory that commemorative medals were struck in London showing Lezo kneeling before him; they had to be quietly withdrawn. Lezo died of illness months later, a hero of the Spanish empire whose one-eyed statue still stands in Madrid.