During the Portuguese Restoration War, the Dutch West India Company occupied the principal settlement of Luanda in 1641, using alliances with local peoples to carry out attacks against Portuguese holdings elsewhere. A fleet under Salvador de Sá retook Luanda in 1648; reconquest of the rest of the territory was completed by 1650. New treaties with the Kongo were signed in 1649; others with Njinga's Kingdom of Matamba and Ndongo followed in 1656. The conquest of Pungo Andongo in 1671 was the last major Portuguese expansion from Luanda, as attempts to invade Kongo in 1670 and Matamba in 1681 failed. Colonial outposts also expanded inward from Benguela, but until the late 19th century the inroads from Luanda and Benguela were very limited. Hamstrung by a series of political upheavals in the early 1800s, Portugal was slow to mount a large scale annexation of Angolan territory.