Complex sentence: He volunteered himself and his Blériot XI airplane to his nation's military, as did his two brothers, Jules and Max. Jan Olieslager was promoted to Sergent, then commissioned before the end of 1914.
Split into simpler sentences: He volunteered himself and his Blériot XI airplane to his nation's military, as did his two brothers. He was promoted to Sergent, then commissioned before the end of 1914.