High Quality Content by WIKIPEDIA articles! The Siege of Gibraltar of 1727 (thirteenth siege of Gibraltar, second by Spain) saw Spanish forces besiege the British garrison of Gibraltar as part of the Anglo-Spanish War. Depending on the sources, Spanish troops numbered between 12,000 and 25,000. British defenders were 1,500 at the beginning of the siege, increasing up to about 5,000. After a five-month siege with several unsuccessful and costly assaults, Spanish troops gave up and withdrew. Following the failure the war drew to a close, opening the way for the 1728 Treaty of El Pardo and the Treaty of Seville signed in 1729.