Frontier forts intended as containment lines instead drove US expansion

Evidence

Fort Leavenworth, Kansas, was initially supposed to mark the “very western edge of civilization” and the “permanent Indian frontier.” However, by protecting the start of the Santa Fe and Oregon trails, it only furthered the westward migration of Euro-American settlers, miners, traders, and farmers. The Army soon became what one historian has called the “advance agent” and “pry bar” of U.S. conquest. … By the middle of the nineteenth century, there were sixty major forts west of the Mississippi River and 138 army posts in the western territories. — David Vine, Base Nation_ How U.S. Military Bases…, 59

Categorization

• QUESTION: The unintended-consequence point — a fort meant to mark a permanent Indian frontier instead prizing open conquest — is a pattern worth tracing through later base chapters.
• corroborated: 2 independent passages support this claim — David Vine, Base Nation_ How U.S. Military Bases…, 59