A civilian guard was first posted at the Tomb on November 17, 1925, to prevent, among other things, families from picnicking on the flat marble slab with views of the city. A military guard was first posted on March 25, 1926. The first 24 - hour guard was posted on midnight, July 2, 1937. The Tomb of the Unknowns has been guarded continuously, 24 hours a day, 7 days a week, since that time. Inclement weather, terrorist attacks, et cetera, do not cause the watch to cease.
when is the tomb of the unknown soldier guarded
continuously