In 1819, Lieutenant John White of the United States Navy was the first American to make contact with Vietnam, arriving in Saigon. Minh Mạng was willing to sign a contract, but only to purchase artillery, firearms, uniforms and books. White was of the opinion that the deal was not sufficiently advantageous and nothing was implemented. In 1821, a trade agreement from Louis XVIII was turned away, with Minh Mạng indicating that no special deal would be offered to any country. That same year, British East India Company agent John Crawfurd made another attempt at contact, but was only allowed to disembark in the northern ports of Tonkin; he gained no agreements, but concluded relations with France posed no threat to Company trade. In 1822, the French frigate "La Cleopatre" visited Tourane (present day Đà Nẵng). Her captain was to pay his respects to Minh Mạng, but was greeted with a symbolic dispatch of troops as though an invasion had been expected. In 1824 Minh Mạng rejected the offer of an alliance from Burma against Siam, a common enemy of both countries. In 1824 Henri Baron de Bougainville was sent by Louis XVIII to Vietnam with the stated mission "of peace and protection of commerce. Upon arriving in Tourane in 1825, it was not allowed ashore. The royal message was turned away on the pretext that there was nobody able to translate it. It was assumed that the snub was related to an attempt by Bougainville to smuggle ashore a Catholic missionary from the Missions étrangères de Paris. Jean-Baptiste Chaigneau's nephew, Eugène Chaigneau, was sent to Vietnam in 1826 as the intended consul but was forced to leave the country without taking up his position.