Mier is a city in northern Mexico, near the Rio Grande.
On December 23, 1842, a band of Texan troops crossed the Rio Grande and entered Mier. They demanded supplies from the town, which the town's alcalde promised to deliver. The troops withdrew and waited. In the meantime, a large detachment of Mexican troops arrived.
On December 25, the two sides engaged in a bloody battle that lasted almost 24 hours. The Texans sustained thirty casualties and ran out of food, water, and ammunition.
More than 200 Texans surrendered to Mexican forces, unaware that they had inflicted an astounding 800 casualties.