Baer was the first American Aviator to be identified as an “Ace” in World War I. He had 9 confirmed and 7 unconfirmed kills. Prior to American involvement in The War, Baer (like many American Flyers), went overseas and joined either England's or France's Air Corps. Baer served with France's Lafayette Flying Corps in 1917. Earning impressive records, he transferred over to The 103rd Aero Squadron (US), upon America's entry into the war. Shot down in 1918, he was a Prisoner of War in Germany. It is speculated that had this not happened, Baer would have possibly gone on to become America's most decorated Aces.
Ever the need for adventure, Baer remained in Europe (with other American Fliers), and joined The Polish Air Force, serving in that Country bid for independence (1919). He returned to America and worked briefly in Civil Aviation. He worked as a Commercial Pilot in South America and China (during which he was killed in a flight accident in 1930). He was credited with over 4,000 hours of flight time. He earned France's Legion of Honor and 2 Distinguished Flying Crosses from The US Army Air Corps.