 Incoming President James Knox Polk directed Brigadier General Zachary Taylor to form an "Army of Observation" at Corpus Christi, Texas, ostensibly to protect the disputed zone from Mexican invasion.Five companies of the 5th Infantry under the command of Lieutenant Colonel James S. McIntosh reported to Taylor at Corpus Christi on 11 October 1845, two days before Texas voters accepted the annexation offer.On 9 March 1846, Taylor's army left Corpus Christi to march to the Rio Grande and assert U.S. sovereignty over the expanded area.