a short time, from January 6, 1937, Tinker served in a light bomber squadron, flying obsolete Breguet 19 bombers. From January 23, he, along with some other American pilots, was assigned to a fighter unit, 1st Escuadrilla de Chatos commanded by Andrés García La Calle, flying Soviet Polikarpov I-15 "Chato" biplanes. In 1937, he flew many combat missions against the Fascist Falange air forces, generally duelling Germans and Italians. The squadron first entered action on February 10, and took part in a Battle of Guadalajara. On March 14, Tinker shot down his first aircraft, an Italian Fiat CR.32 fighter, followed by another CR.32 on March 20. On April 17, he shot down a German Heinkel He 51 fighter from Legion Condor over Teruel. On May 3, 1937, Tinker was assigned to 1st Escuadrilla de Moscas, commanded by the Russian, Ivan Lakyeyev, flying the faster Polikarpov I-16 "Mosca" monoplane fighters. On June 2 and June 16, he shot down another CR.32. On July 13, he became the first pilot to shoot down one of the most modern German fighters, a Messerschmitt Bf 109A, near Madrid. It was piloted by Unteroffizier Guido Honess of 2. Staffel/Jagdgruppe 88 (2./J 88), flying a Bf 109A believed to be marked 6–4. Honess, who was killed in the ensuing crash, was the first German pilot to achieve three victories with this new type of aircraft. On July 17, Tinker shot down another Bf 109A. This first version of the Bf 109 was not a "good climber" and Tinker caught it from behind while the German pilot tried to gain altitude after a dive on him – a lethal mistake according to Tinker. The scene is described in detail in his book Some Still Live. His final victory was over a Fiat CR.32 on July 18, 1937. Tinker flew his last missions on July 29, 1937, then returned to the U.S. While in Spain, Tinker socialized with Ernest Hemingway, Robert Hale Merriman, the leader of the American Volunteers of the Lincoln Brigade and his successor Milton Wolff, who led the 15th International Brigade during the Battle of the Ebro. Later years and death Eventually, Tinker fell victim to combat stress reaction due to the constant combat. After the war, Tinker was a guest speaker in New York on the radio program "We the People", discussing his feats in the Spanish Civil War. He wrote a number of