Complex sentence: Karl Baedeker III, the fourth son, entered academia and rose to become a professor of physics at the University of Jena, but he was killed in action at the Battle of Liège in August 1914.
Split into simpler sentences: Karl Baedeker III, the fourth son, entered academia and rose to become a professor of physics at the University of Jena. He was killed in action at the Battle of Liège in August 1914.