When the Gadsden Purchase was completed in 1854, Mexico received $10 million from the United States for the 29,670 square miles of territory, south of Gila River, which the U.S. government added to the New Mexico Territory. At the time, the only military presence in the vast purchase area was the Mexican force stationed at the Tucson presidio. In November 1856, four companies of U.S. dragoons arrived with orders to establish a garrison in the vicinity of Tucson. After scouting the area, they established Fort Buchanan, named for the new president, at the headwaters of Sonoita Creek on the eastern side of the Santa Rita Mountains.
As the troops stationed at Ft. Buchanan chased down outlaws, tried to counter Apache raids and provided protection for the Butterfield stage line, the national political consensus was unraveling due to sectional quarrels over the issues of states’ rights and slavery. Regrettably, President Buchanan and the other national politicians of the day failed to find a peaceful resolution to the sectional crisis. After President Lincoln took office, hostilities erupted in South Carolina in April 1861. As a result, Fort Buchanan was abandoned in July 1861, its troops transferred to places more vital to the war effort. Fortunately for the fragmenting United States, the European powers decided to stay mostly on the sidelines. In America, the Lincoln administration fought a bloody Civil War as slavery and its attendant issues were settled by four years of warfare.