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.