George Whitefield (1714-1770) introduced John Wesley to outdoor preaching. Here, Whitefield is depicted preaching to a gathering in Leeds in 1749.
Both Whitefield and John Wesley were charismatic preachers who stirred the masses. In the mid 1700s, outdoor revival meetings like these could be unruly and violent. Often, large crowds were being told of the transforming power of God and the choice between heaven and hell.