Battle road of General Zachary Taylor and largest U.S. Army fielded in first half of the 19th century. After annexation of former Republic of Texas was approved in 1845, the United States sent Taylor to occupy area below the Nueces-- to support claim to all land east of the Rio Grande. In August 1845 he reached Corpus Christi where he waited while U.S. and Mexico tried to reach boundary agreement. He also sent out engineers to map a road parallel to the Gulf, where the U.S. Navy watched the crisis. His army-- including on its rosters two later U.S. presidents and later many statesmen and generals-- drilled throughout a rainy winter. On orders from Washington, it moved toward Rio Grande in March 1846. Along its path were few people but much game-- wild cattle, antelope, deer, mustang horses, wild turkeys. Although challenged about 70 miles south of here by a Mexican patrol, Taylor proceeded to occupy Rio Grande Valley. April attacks and may battles of Palo Alto and Resaca de la Palma caused the United States to declare war. Afterward many troops took this road and joined the fighting, which fixed the Rio Grande as boundary and gained for U.S. lands now in Arizona, California, Nevada and New Mexico.