In the 18th century, a small opposition developed against the slave trade in Britain, America, and some parts of Europe. In Britain and America, opposition to the trade was led by the Religious Society of Friends (Quakers) and establishment Evangelicals such as William Wilberforce. People who protested against the trade were opposed by the owners of land in the Americas. After 1772, slaves became free upon entering the British isles. Abolitionism became stronger in the 19th century.