Quakers in the abolition movement

The Religious Society of Friends, better known as the Quakers, played a major role in the abolition movement against slavery in both the United Kingdom and in the United States. Quakers were among the first groups to formally and consistently oppose slavery in the American colonies and Europe, and the Society of Friends became the first organization to take a collective stand against both slavery and the slave trade, later spearheading the international and ecumenical campaigns against slavery.

Source: Wikipedia — Quakers in the abolition movement (CC BY-SA 4.0)