Muscat's naval and military supremacy was re-established in the 19th century by Said bin Sultan, who signed a treaty with U.S. President Andrew Jackson's representative Edmund Roberts on September 21, 1833. Having gained control over Zanzibar, in 1840 Said moved his capital to Stone Town, the ancient quarter of Zanzibar City; however, after his death in 1856, control over Zanzibar was lost when it became an independent sultanate under his sixth son, Majid bin Said (1834/5–1870), while the third son, Thuwaini bin Said, became the Sultan of Oman.