During the 1820s and 1830s, the solution of the American Colonization Society (ACS) to the presence of free blacks was to persuade them to emigrate to Africa. In 1821, the ACS established the colony of Liberia, and persuaded thousands of former slaves and free black people to move there. Some slaves were manumitted (set free) on condition that they emigrate. The slave states made no secret that they wanted to get rid of free blacks, who they believed threatened their investment, the slaves, encouraging escapes and revolts. The support for the ACS was primarily Southern. The founder of the ACS, Henry Clay of Kentucky, stated that because of "unconquerable prejudice resulting from their color, they never could amalgamate with the free whites of this country. It was desirable, therefore, as it respected them, and the residue of the population of the country, to drain them off". Thousands of black people were resettled in Liberia, where they formed an American English speaking enclave which could not assimilate back into African life and as a result, most of them died of tropical diseases.