Let’s get right to it. The number 3 spot is the Battle of Medina. Fought on the 18th day of August in 1813, this battle has the singular honor of being the bloodiest battle in Texas history, with around 1,300 men killed in a single day.
Sidebar: technically, it is only the second-bloodiest battle: if you interpret "bloodiest" to mean, "greatest number of gallons of blood which have ceased their job of carrying oxygen to the cells of living beings," the honor would have to go the the Battle of Palo Duro Canyon, where over 1,000 horses were killed by the U.S. Army. By driving them off a cliff. But we'll assume that dead people are more important.
The official description of the Battle of Medina is fairly succinct, and unfortunately avoids much of the deeper issues at play during the Gutierrez-Magee filibuster expedition. Suffice it to say that the filibusters and Mexican patriots woefully underestimated the Spanish military discipline and walked right into an ambush.
Aside from the sheer number of dead fighters, I find this battle distinct in how one-sided it is. The Spanish claimed to have only lost 55 men (assuming that Arredondo was honest), which is about 5% of the filibuster losses. Most battles of this era had a more even scale of casualties on both sides. Additionally, an army equipped with Kentucky long rifles should have been able to inflict devastating losses on an enemy force long before they could close the distance for melee fighting.
The mystery becomes clear when one reads the survivor accounts: they agree that the filibusters had allowed themselves to get spread out in a long line, in a mad race to catch the “cowardly” Spanish. Their previous experiences with Spanish soldiers in Texas had led them to assume their enemy would simply run away, and so they were led straight into a death trap.
This battle also indirectly led to the Texas Revolution, simply due to the staggering loss of life after Arredondo had completed his purge. Sources say that Texas lost about one third of its total Tejano population within two years of the Battle of Medina – nobody wanted to stick around in Texas unless they absolutely had to. This opened up the possibility for some other groups of people who might be interested in moving to Texas (but don’t worry, most of them promised that they were fine upstanding people, with absolutely no arrest warrants in their names)
Tomorrow: Our important battle list continues with number 2! Will it involve Davy Crockett? Only one way to find out!