Fort Buchanan was established by the United States Army along the Sonoita River in present-day southern Arizona, primarily to manage and secure the lands acquired through the Gadsden Purchase, which was finalized in the 1850s. The fort became vital in controlling the region, as it was a key area for settlement and expansion during a time when tensions were high between the United States and indigenous populations, as well as with Mexico. The location was selected for its strategic advantages, including access to water and proximity to local trails used by settlers and traders.

The Gadsden Purchase was an agreement that allowed the U.S. to acquire additional land from Mexico, and Fort Buchanan was part of a broader military strategy to protect and facilitate the movement of settlers into these newly acquired territories. The U.S. Army aimed to create a supportive environment for settlers and promote the orderly growth of American territories. The fort housed troops who were tasked with patrolling the area and engaging with various tribes, ensuring that the interests of the United States were represented and maintained across the Southwestern frontier.

As the fortages grew, so did the challenges. The presence of the military often escalated conflicts with Native American tribes, who resisted encroachment on their lands. This resulted in numerous skirmishes and a complicated relationship between the settlers, the military, and indigenous populations. Over time, Fort Buchanan contributed to the landscape and settlements that emerged in southern Arizona, shaping the area’s social and economic dynamics.