In 1848, the U.S. Secretary of War ordered Lieutenant Colonel Edwin V. Sumner, commander of the Ninth Military Department, to revise the whole system of defense in the New Mexico Territory by moving U.S. troops out of towns and closer to the Native American presence there. To do so, Sumner established Fort Union on July 12, 1851, near the junction of the Mountain and Cimarron Branches of the Santa Fe Trail. The site was considered ideal for projecting the power of the United States government, and when active the fort encompassed a 44,000 acre military reservation. Because of its remote location, it had to be large enough to sustain both troops and associated civilians. On July 12, 1851, Captain John Pope wrote that the grass was abundant and of excellent quality, wood was plentiful nearby, there were many springs of clear, cold water in the vicinity, and the valley was by far the most desirable country he had seen since leaving Missouri.