Complex sentence: Diehl's involvement in Democratic Party affairs began at Austin College, first working in the reelection campaign of United States Senator Ralph Yarborough, then organizing students and the neighboring African American community on behalf of local reform candidates.
Split into simpler sentences: Diehl's involvement in Democratic Party affairs began at Austin College, working in the reelection campaign of United States Senator Ralph Yarborough. He also organized students and the neighboring African American community in support of local reform candidates.