The roots of African-American Methodism in this area can be traced to the late 18th century when Methodism pioneers such as Francis Asbury and Freeborn Garrettson traveled locally organizing black "classes" for worship. Over time some groups chose to leave the mother church, while others such as this congregation remained affiliated with the Methodist Episcopal faith. By the mid-1800's members of Union Wesley were gathering regularly for services. Many of the early meetings were conducted in the open air nearby.
On December 18, 1873, the trustees of Union Wesley purchased the lot where the first church was built. Standing in the area where the cemetery is located, the building served the needs of the congregation until it was destroyed by fire in 1957. The present church was erected here on the former site of the District #207-C Blackwater School. The land had been obtained in 1951 following the destruction of the school by fire. The new church was completed in 1961.
Prior to the placement of permanent structures on the Wesley Campground, persons attending services used covered wagons for shelter. The wagons were placed in a circle surrounding a pulpit. By the 1930's wooden boarding "tents" had replaced the wagons, and a confectionery and bower had been constructed. One building that was adapted for use was the old #207-C Schoolhouse. Constructed in the late 19th century, the structure was used as a school until 1922, when it was replaced by the building that stood on this site. This was the last camp in Delaware to use wooden firestands for lighting purposes. Their use was discontinued in 1943 when electricity was brought to the grounds. Wesley Campground is believed to be one of the oldest of its type in continuous use.