De Haro realized that an invasion was inevitable and ordered Captain Juan de Amézqueta and 300 men to defend the island from El Morro Castle and then had the city of San Juan evacuated. He also had former governor Juan de Vargas organize an armed resistance in the interior of the island. On September 25, Hendricksz attacked San Juan, besieging El Morro Castle and La Fortaleza (the Governor's Mansion). He invaded the capital city and set up his headquarters in La Fortaleza. The Dutch were counterattacked by the civilian militia on land and by the cannons of the Spanish troops in El Morro Castle. The land battle left 60 Dutch soldiers dead and Hendricksz with a sword wound to his neck which he received from the hands of Amézqueta. The Dutch ships at sea were boarded by Puerto Ricans, who defeated those aboard. After a long battle, the Spanish soldiers and volunteers of the city's militia were able to defend the city from the attack and save the island from an invasion. On October 21, Hendricksz set La Fortaleza and the city ablaze. Captains Amézqueta and Andrés Botello decided to put a stop to the destruction and led 200 men in an attack against the enemy's front and rear guard. They drove Hendricksz and his men from their trenches and into the ocean in haste to reach their ships. Hendricksz upon his retreat left behind him one of his largest ships, stranded, and over 400 dead. He then tried to invade the island by attacking the town of Aguada. He was again defeated by the local militia and abandoned the idea of invading Puerto Rico.