San Juan Expedition (1780)

San Juan Expedition
Part of the American Revolutionary War
Captain Horatio Nelson, painted by John Francis Rigaud in 1781, with Fort San Juan in the background.
Date 17 March – 8 November 1780 Location San Juan River, present-day Nicaragua Result Spanish victory[1]
Belligerents
Spain New Spain Captaincy General of Guatemala	Great Britain
Commanders and leaders
Matías de Gálvez Juan de Ayssa	John Polson † Horatio Nelson
Strength
160 regulars and militia (Fort San Juan) 500 militia (Granada's outskirts)[2]	3,000 regulars, militia, sailors and irregulars[3] 1 frigate 2 brigs 3 sloops 1 tender 1 transport[2][4]
Casualties and losses
Unknown killed or wounded 45 captured[5]	2,500 killed or died of disease[6] 2 ships grounded[4]

The San Juan Expedition took place between March and November 1780 during the American War of Independence when a British force under the command of John Polson and Captain Horatio Nelson landed on the coast of the present-day Nicaragua, with the aim of sailing up the San Juan River to capture the strategically crucial towns of Granada and León, located on the northwestern shore of Lake Nicaragua.

Despite an initial success in the capture of the Fortress of the Immaculate Conception, Polson's force never reached Lake Nicaragua and, decimated by yellow fever, was forced to return to Jamaica. The campaign ended in total failure and cost the lives of more than 2,500 men, making it the costliest British disaster of the entire war.^[6]