http://en.wikipedia.org/wiki/John_Mercer_Langston

Together with his older brothers Gideon and Charles, John Langston became active in the Abolitionist movement. He helped runaway slaves to escape to the North along the Ohio part of the Underground Railroad. In 1858 he and Charles partnered in leading the Ohio Anti-Slavery Society, with John acting as president and traveling to organize local units, and Charles' managing as executive secretary in Cleveland.

In 1868 Langston moved to Washington, D.C. to establish and serve as dean of Howard University's law school; it was the first black law school in the country. Appointed acting president of the school in 1872, and vice president of the school, Langston worked to establish strong academic standards. He also hoped to create the kind of open environment he had known at Oberlin College. Langston was passed over for the permanent position of president of Howard University School of Law by a committee that refused to disclose the reason.

President Ulysses S. Grant appointed Langston a member of the Board of Health of the District of Columbia. In 1877 President Hayes appointed Langston as U.S. Minister to Haiti; he also served as chargé d'affaires to the Dominican Republic.

In 1885 Langston returned to the US and Virginia, where he was named the first president of Virginia Normal and Collegiate Institute, a historically black college (HBCU) at Petersburg. There he also began to build a political base. In 1888, Langston was urged to run for a seat in the U.S. House of Representatives by fellow Republicans, both black and white. Leaders of the biracial Readjuster Party, which had held political power in Virginia from 1879–1883, did not support his candidacy. Langston ran as a Republican and lost to his Democratic opponent. He contested the results of the election because of voter intimidation and fraud. After 18 months Langston was declared the winner and took his seat in the US Congress. He served for the remaining six months of the term.