What mission did General Carl A. "Tooey" Spaatz launch in 1929 to demonstrate aerial refueling?

The mission that General Carl A. "Tooey" Spaatz launched in 1929 to demonstrate aerial refueling is known as the Question Mark mission. This pioneering operation involved a group of three Army Air Service aviators who refueled a modified Douglas C-1 aircraft in mid-air, showcasing the feasibility of aerial refueling for extending the range and endurance of military aircraft. The success of the Question Mark mission was significant in proving that aircraft could remain aloft for extended periods, which was a critical development for future military operations and aviation strategies. This mission also served to highlight the importance of aerial refueling as a tactical advantage in ensuring that aircraft could operate far from their home bases without the need for landing to refuel.