Some 20,000 people were relocated against their will during the Cherokee removal, part of the Trail of Tears. Notably, Ralph Waldo Emerson, who would go on to become America's foremost man of letters, wrote Van Buren a letter protesting his treatment of the Cherokee. The administration also contended with the Seminole Indians, who engaged the army in a prolonged conflict known as the Second Seminole War. Prior to leaving office, Jackson put General Thomas Jesup in command of all military troops in Florida to force Seminole emigration to the West. Forts were established throughout the Indian territory, and mobile columns of soldiers scoured the countryside, and many Seminoles offered to surrender, including Chief Micanopy. The Seminoles slowly gathered for emigration near Tampa, but in June they fled the detention camps, driven off by disease and the presence of slave catchers hoping to capture Black Seminoles. In December 1837, Jesup began a massive offensive, culminating in the Battle of Lake Okeechobee, and the war entered a new phase of attrition. During this time, the government realized that it would be almost impossible to drive the remaining Seminoles from Florida, so Van Buren sent General Alexander Macomb to negotiate peace with them. It was the only time that an Indian tribe had forced the government to sue for peace. An agreement was reached allowing the Seminoles to remain in southwest Florida, but the peace was shattered in July 1839 and was not restored until 1842, after Van Buren had left office. Just before leaving office in March 1837, Andrew Jackson extended diplomatic recognition to the Republic of Texas, which had gained de facto independence from Mexico in the Texas Revolution. By suggesting the prospect of quick annexation, Jackson raised the danger of war with Mexico and heightened sectional tensions at home. New England abolitionists charged that there was a "slaveholding conspiracy to acquire Texas", and Daniel Webster eloquently denounced annexation. Many Southern leaders, meanwhile, strongly desired the expansion of slave-holding territory in the United States. Boldly reversing Jackson's policies, Van Buren sought peace abroad and harmony at home. He proposed a diplomatic solution to a long-standing financial dispute between American citizens and the Mexican government, rejecting Jackson's threat to settle it by force. Likewise, when the Texas minister at Washington, D.C., proposed annexation to the administration in August 1837, he was told that the proposition could not be entertained. Constitutional scruples and fear of war with Mexico were the reasons given for the rejection, but concern that it would precipitate a clash over the extension of slavery undoubtedly influenced Van Buren and continued to be the chief obstacle to annexation.