The Battles of Lexington and Concord: it was in April 19th

[Savago]

Nice article about the subject:
https://www.history.com/topics/american-revolution/battles-of-lexington-and-concord

Those battles kicked off the American Revolutionary war and showed that a group of militiamen could stand against the army of the most powerful nation (England) at the time.

It all started because the British wanted to confiscate our guns (historically accurate AR-15 in the photo below).