“Barricade” came to English via the Middle French barricade, literally meaning “made of barrels.” Its association with war and revolution comes from religion-fueled riots in Paris during the late 1500s, when combatants set up blockades made of stone- and dirt-filled barrels in the streets.
These riots were part of the French Wars of Religion, fought between French Roman Catholics and Calvinist Huguenots. Riots and battles took place all across the Kingdom of France from 1562 and 1598, but much of the mob violence was concentrated in Paris, where the majority of the population was Catholic, including the infamous St. Bartholomew’s Day massacre. During the riots (and many later revolutionary scraps in Paris, such as the June Rebellion, around which Victor Hugo’s Les Misérables is centered), barrels were filled with stones and dirt and set up in the streets of Paris to form makeshift blockades and ramparts.
While “barricade” came to English via the Middle French barricade—though some sources say the Spanish barricada is earlier. Regardless, both are from barrica “barrel.” The English word “barrel” is directly from the Old French baril “barrel, cask, vat.”
Interestingly, “barricade” and “barrel” do not appear to be directly related to “barrier,” which is from the Old French barriere, meaning “obstacle, gatekeeper,” from barre “bar,” originally from the Vulgar Latin *barra, “bar, barrier, rod.” According to Wiktionary:
An attempt to link baril to Old French barre… via assumed Vulgar Latin *barrīculum meets the phonological requirement, but fails to connect the word semantically.
Instead, the more plausible source of “barrel” is Frankish or Gothic (*baril or *beril), originally from Proto-Germanic *barilaz (“barrel, jug, container”).