This webpage about the patron saint of French army aviation is pretty interesting! (Read it on Google Translate.)
Originally, they planned to pick St. Elijah the Prophet, because of the “chariot of fire.” (And apparently some wish this had happened, because his French name, Elie, sounds like the French “helie” for helicopters.) They also wanted a summer feast day, so they could fly and have fun while honoring the saint; and St. Elijah’s feast is in July. (As opposed to St. Barbara, patron of artillery and guns, whose feast is in cold December.)
But then came the liberation of Rome in WWII on June 4th, which was St. Clotilde’s Day. Small Free French army aircraft were used for observation work, during the fight. And so the French aviators took the date of victory as a sign.
The webpage includes a beautiful prayer to St. Clotilde for her intercession!