In April 1929 in the town of Naco, Arizona, the Cristero War was raging just over the border in Mexico. Rebels in that conflict had hired pilots and rickety wood-and-canvas biplanes to drop homemade bombs on their enemies, the government Federales. Throughout the day people on the Arizona side of Naco crowded atop boxcars, picnicking and playing with children while watching the spectacle of battle from what seemed to be a safe distance.
One of the Mexican rebels’ hired pilots was an American biplane owner named Patrick Murphy. The rebels paid Murphy to fly high above the battlegrounds with “suitcase bombs” strapped the sides of his fuselage. Due to some combination of high winds and stiff drinks, he occasionally lost his way and flew over the border to the American side of town. He popped open his suitcases, releasing slapdash canisters full of dynamite, nails, nuts, bolts, and bearings. Civilians scattered as the blasts shattered windows, destroyed a car, lightly battered some bystanders, and ruffled American military feathers.
Mexican Federales forces shot Murphy’s plane down on the 7th of April over Mexico, but he survived the rough landing and fled back to the safety of his home on US soil. He was promptly arrested. For reasons lost to time, Murphy was released a few days later, never criminally charged for his role in the first aerial bombardment of the continental United States by a foreign power.