In May 2021, during its conflict with Hamas, the Israel Defense Forces became the first military to use a drone swarm in combat. Not much is known about the event, other than that Israel used the drone swarm to strike “dozens” of targets in concert with other missiles and munitions. Often media outlets use the phrase “drone swarm” to just mean many drones used at once. But this was  a true drone swarm, meaning the drones communicated and collaborated in making collective decisions.

Source : Swarm Talk: Understanding Drone Typology | RealClearDefense