First siege of Callao

First siege of Callao
	Part of the Peruvian War of Independence
	; Cochrane's fleet blockades Callao by sea
Date	13 June–19 September 1821
Location	Callao, Viceroyalty of Peru12°1′59.99″S 77°7′59.99″W / 12.0333306°S 77.1333306°W
Result	Patriot victory
Belligerents
Liberating Expedition; Peruvian patriots;	Spain Viceroyalty of Peru;
Commanders and leaders
José de San Martín; Thomas Cochrane;	José de la Mar ; Manuel Arredondo
Strength
7,000 men; 8 warships	2,000 soldiers and militiamen; 3 warships; Several armed merchant ships
Casualties and losses
Unknown	400 casualties
	Location within Lima First siege of Callao (Peru) First siege of Callao (South America)

The first siege of Callao was a prolonged military blockade of the Real Felipe Fortress (as well as other fortresses) in Callao by the Liberating Expedition of Peru under the command of General José de San Martín in July 1821 which culminated in the capitulation of Marshal José de La Mar in September of the same year, with him switching sides from the Royalist side to the Patriot side.