The 125th Observation Squadron was organized in December 1940 as the Oklahoma National Guard's first flying unit in Tulsa, Oklahoma. It was federally recognized in January 1941. For the next three and a half years the squadron was attached to the 77th Observation Group and the 76th Reconnaissance Group at various locales in the United States before arriving at Liverpool, United Kingdom on D-Day, 6 June 1944. After moving across the English Channel to France in August 1944, the 125th Liaison Squadron was attached to the U.S. Ninth Army until V-E Day, participating in the campaigns of northern France, Ardennes, Rhineland and Central Europe, and was awarded the Belgian Fourragère for gallantry during the Battle of the Bulge in July 1945. Over the course of those five years, the 125th flew the Douglas 0-38E, the Curtiss O-52 Owl, and the Stinson L-5 Sentinel.