Battle of San Fernando de Omoa The Battle of San Fernando de Omoa was a short siege and battle between British and Spanish forces fought not long after Spain entered the American Revolutionary War on the American side . On 16 October 1779 , following a brief attempt at siege , a force of 150 British soldiers and seamen assaulted and captured the fortifications at San Fernando de Omoa in the Captaincy General of Guatemala ( now Honduras ) on the Gulf of Honduras . The British forces managed to overwhelm and capture the Spanish garrison , consisting of 365 men . The British only held the fort until November 1779 . They then withdrew the garrison , which tropical diseases had reduced , and which was under threat of a Spanish counter - attack . Background . When Spain entered the American Revolutionary War in June 1779 , both Great Britain and Spain had been planning for the possibility of hostilities for some time . King Carlos III set the defense of the Captaincy General of Guatemala as one of his highest priorities in the Americas , after the conquest of British West Florida . His forces seized the initiative in North America , where they rapidly captured the British outpost at Baton Rouge in September 1779 , before the British were able to marshal significant defensive forces in the area . The British sought to gain control over Spanish colonies in Central America , and their first target was San Fernando de Omoa , a fortress that Matías de Gálvez , the Captain General of Guatemala , called " the key and outer wall of the kingdom " . However , the Spanish struck first . In September the capture of Cayo Cocina gave them possession of the British settlement at St . George ' s Caye ( off the coast near present - day Belize City ) . Then , anticipating a British attack against the nearby port of Santo Tomás de Castilla , Gálvez withdrew the garrison there to Omoa . The Spanish had started building San Fernando de Omoa , principally with African slave labour , in the 1740s during the War of Jenkins ' Ear . It became of the largest defensive fortifications in Central America , and one of the Guatemalan Captaincy General ' s principal Caribbean ports . British forces . The decision by Gálvez to withdraw to Omoa upset British plans . Commodore John Luttrell , in command of three ships and 250 men , had intended an attack on the Santo Tómas , but his force was inadequate for an attack on Omoa . Even when he and Captain William Dalrymple arrived at Omoa on 25 September with 500 men , they were forced to retreat after a brief exchange of cannon fire . The British returned with a force of more than 1 , 200 men and twelve ships in early October . Battle . The British established some batteries to fire on the fort , and supported them with fire from three ships . Simón Desnaux , the fort ' s commander , returned fire . He succeeded in damaging , which ran aground but was eventually refloated . Although , Desnaux was badly outnumbered , he refused an offer for surrender , in the hope that Gálvez would be able to send reinforcements . On the night of 20 October , a small number of British attackers climbed into the fort and opened one of the gates . After a brief exchange of small arms fire , Desnaux surrendered . Among the spoils the British won when they gained control of Omoa were two Spanish ships , anchored in the harbor , that held more than three million Spanish dollar s of silver . Counterattack . Gálvez immediately began planning a counterattack . On 25 November his forces began besieging the fort , now under Dalrymple ' s control , engaging in regular exchanges of cannon fire . Gálvez , whose force was smaller than Dalrymple ' s , magnified its apparent size by setting extra campfires around the fort . He then attempted an assault on 29 November but difficulties with his artillery caused him to call it off . Still , Dalrymple , whose forces were significantly reduced by tropical diseases , withdrew his men from the fort and evacuated them that same day . Aftermath . The British continued to make attacks on the Central American coast but were never successful in their goal of dividing the Spanish colonies and gaining access to the Pacific Ocean . Equally , the Spanish were unsuccessful in driving out the British settlements in Central America , most of which the British had recaptured by the war ' s end .