Tet de Mayo
Cinco de Mayo isn’t much of a holiday, but what makes the Battle of Puebla important was that is was the Tet Offensive of the 19th century. It didn’t really matter so much that the French were able to occupy Mexican cities when a cobbled-together peasant army showed it could defeat what at the time was the best and most technically advanced army in the world. And that there was an organized national reistance movement capable of not only continuing the resistance, but of maintaining a functional government.
And that nerds can be heroes too: