Monterrey, Battle of, September 20–24, 1846, a United States victory in the Mexican War. General Zachary Taylor advanced on Monterrey, Mexico, with about 6,000 men to face 8,000 defenders. The city was taken only after fierce house-to-house fighting. The Mexicans surrendered on condition that they be allowed to leave the city unimpeded and that an eight-week armistice be granted. United States casualties were 120 killed and 368 wounded; Mexican losses were 367 killed and wounded.