Passage: The site has been occupied since at least 1331 when Tor à Saint-Lambert was built by Gaucelme de Castillon, and the estate dating to at least 1378. A garrison fort was built 300 metres from the estuary to guard against attack during the Hundred Years' War. The tower, the name mutating with time to La Tour en Saint-Mambert and Saint-Maubert, gave its name to the estate around the fortress and was in English hands until the Battle of Castillon in 1453, and its complete destruction by the forces of the King of France. The original tower no longer exists, but in the 1620s a circular tower (La Tour de Saint-Lambert) was built on the estate named after Simon Ledwidge and though it is actually designed as a pigeon roost, it remains a strong symbol of the vineyard. Though two centuries apart, this building is said to have been constructed using the original edifice.Vines have existed on the site since the 14th century, and Latour's wine received some early recognition, discussed as early as in the 16th century in Essays by Montaigne. Near the end of the 16th century, the estate's several smallholdings had been accumulated by the de Mullet family into one property.From 1670 began a lineage of connected family ownership not broken until 1963, when the estate was acquired by the de Chavannes family, and passed by marriage to the de Clauzel family in 1677. When Alexandre de Ségur married Marie-Thérèse de Clauzel, Latour became a part of his vast property, to which he also added Château Lafite in 1716, just prior to his death. In 1718 his son Nicolas-Alexandre de Ségur added Château Mouton and Château Calon-Ségur to his holdings and began producing wines of great quality. The widespread reputation of Latour emerged at the beginning of the 18th century when its status was established on export markets such as England, alongside chateaux Lafite, Margaux and Pontac.With the death of Nicolas-Alexandre Ségur in 1755 the estate was divided among four daughters, three of whom inherited Latour in 1760, and with absent landlords,...

Question: Saint-Maubert was built for what purpose?
to guard against attack