CARLISLE, Pennsylvania — Cradled in the Cumberland Valley, just west of the Susquehanna, and flanked by the Blue Mountain range to the north and the northernmost tip of the Blue Ridge Mountains to the south, sits the Carlisle Barracks. It is one of our nation’s oldest military installations, dating back to its inception as an outpost in the 1750s. Back then, Carlisle was simply an intersecting trade route developed by the native tribes. Traders,…