Complex sentence: On April 15,1871, Hickok became marshal of Abilene, Kansas, taking over from former marshal Tom "Bear River" Smith, who had been killed on November 2,1870.
Split into simpler sentences: On April 15,1871, Hickok became marshal of Abilene, Kansas. He replaced former marshal Tom "Bear River" Smith, who had been killed on November 2,1870.