The Battle of Karánsebes (1788). During one of the many Habsburg-Ottoman Wars, a Habsburg army was setting up camp near the town of Karánsebes, near the Timiș River in Transylvania. As the main force of the army set up camp, a contingent of hussars crossed the river to scout for the Ottomans. They didn't find any Ottomans, but they
did find some local merchants travelling in the opposite direction with a whole bunch of schapps for sale. The hussars started drinking as they waited for the main force of the army to catch up. Meanwhile, the army crossed the river, and ran into the same merchants -- who also ran into the same merchants. They also bought a ton of schnapps, and got drunk as they moved forward.
When the infantry saw the hussars on the horizon, they mistook their own scouts (also drunk) for the Ottoman cavalry, and proceeded to attack. Now, the infantry was made up of many different nationalities, but the hussars themselves were Germans. So when the hussars started yelling, "Halt! Halt!," the non-Germans in the infantry misheard it as "Allah! Allah!" From there, it devolved into a great drunken fight, with hundreds dead -- according to legend and lore, there were ten-thousand; though modern estimates say it was closer to one-thousand before everyone stopped fighting and ran away in confusion.
Two days later, the Ottoman Army actually
did turn up. With the Habsburg forces already dead, they occupied Karánsebes without issue.