After British Admiral Edward Vernon won a huge victory at Portobelo, General James Oglethorpe, the founder of Georgia, was quick to imitate him in North America. In June 1740, Oglethorpe and a British fleet of seven ships appeared off St. Augustine. As in the 1702 siege, three hundred soldiers and 1,300 residents found refuge within the Castillo's walls. For 27 days the British bombarded the Castillo and St. Augustine. Realizing his cannon were not affecting the Castillo's walls of coquina, Oglethorpe decided to starve the people of St. Augustine by blockading the inlet at the Matanzas River and all roads into St. Augustine. However, some supplies were able to reach the city via the river, and with morale and supplies low for the British forces, Oglethorpe had to retreat. In order to protect the city from future blockades and sieges, the Spanish built Fort Matanzas to guard the river, which could be used as a rear entrance to avoid St. Augustine's primary defense system.