Complex sentence: Martin Edward Dempsey (born March 14,1952), sometimes known as Marty Dempsey, is a retired United States Army general who served as the 18th Chairman of the Joint Chiefs of Staff from October 1,2011 until September 25,2015.
Split into simpler sentences: Martin Edward Dempsey (born March 14,1952), sometimes known as Marty Dempsey, is a retired United States Army general who served as the 18th Chairman of the Joint Chiefs of Staff. Dempsey assumed his assignment as Chairman of the Joint Chiefs of Staff on October 1,2011 and stepped down from the Chairmanship on September 25,2015.