One of the earliest endeavors to remember the fallen occurred soon after the war concluded. Union troops stationed at nearby Fairfax Court House, many of whom has recently served on burial duty at the battlefield, recognized the need for a fitting memorial to the Federal dead of First Manassas. With the approval of their officers and the authorization of the government, and in one of their final acts before discharge, the soldiers erected the Bull Run monument. Construction took nearly three weeks and was completed in June 1865. It remains one of the oldest extant monuments on any Civil War battlefield.
Source: U.S. Department of the Interior, National Park Service