This considers the role of Thomas Clarkson as peace campaigner. Clarkson played a leading role in the campaign to abolish the slave trade in the 1780s. Much of his thinking about peace was influenced by the prospects of colonial development. His Portrait of Quakerism (1806), a pioneering explanation of pacific Quaker principles, was followed by his Memoirs of William Penn (1813), the pacifist founder of Pennsylvania, which recommends setting up seminaries to teach the children of the rich, and offers Penn as a model of peaceful colonial relations. As a member of the Africa Institution and the Sierra Leone Company, Clarkson was personally involved in plans for peaceful colonizing. This interest is reflected in The Herald of Peace, the journal of the Peace Society Clarkson helped to establish, in which the example of Penn is often cited. The peace campaign was rooted in the goal of spreading Christianity and European influence globally.