An estimated 700,000 Union and Confederate soldiers died in the Civil War between April 1861 and April 1865, and as the death toll rose, the U.S. Government struggled with the urgent but unplanned need to bury fallen Union troops, helping propel the creation of a national cemetery system. On September 11, 1861, the War Department directed commanding officers to keep accurate and permanent records of deceased soldiers and required the U.S. Army Quartermaster General to mark each grave with a headboard, and a few months later it mandated interment in graves marked with numbered headboards and recorded in a register. Authority to create military burial grounds came in an Omnibus Act of July 17, 1862, directing the president to purchase land for national cemeteries for soldiers who died in service, and fourteen national cemeteries were established by 1862. After the war, in October 1865, Quartermaster General Montgomery C. Megis directed officers to survey lands in the Civil War theater to find Union dead and plan to reinter them in new national cemeteries, with sites chosen where troops had concentrated at camps, hospitals, battlefields, and railroad hubs. By 1872, seventy-four national cemeteries and several soldiers' lots contained 305,492 remains, about 45 percent of them unknown. Congress funded permanent walls or fences, grave markers, and lodges for cemetery superintendents in the Act to Establish and to Protect National Cemeteries of February 22, 1867. At first only soldiers and sailors who died during the Civil War were buried in national cemeteries, but in 1873 eligibility expanded to all honorably discharged Union veterans, Congress appropriated $1 million to mark graves, upright marble headstones honored known individuals, and six-inch-square blocks marked unknowns. By 1873, military post cemeteries on the Western frontier had joined the system, and the National Cemeteries Act of 1973 transferred eighty-two Army cemeteries, including twelve of the original fourteen, to what is now the National Cemetery Administration. The country also reflected on the war's human toll, with 2 percent of the U.S. population dead, and memorials honoring service were built in national cemeteries, most donated by regimental units, state governments, and veterans' organizations such as the Grand Army of the Republic. Decoration Day, later Memorial Day, began in 1868 as a popular patriotic spring event when visitors placed flowers on graves and monuments and gathered to hear speeches, and by 1920 more than 120 monuments had been placed in national cemeteries after monument construction peaked in the 1890's.