As U.S. bases are shut down, many memorial items, dating from World War II, are being moved, sometimes to be scrapped. Those involved in the removals are warned to remember a 1958 incident. Back then, a British air base, at Scampton, was rebuilding the road through the main gate. There were two "gate guards" on either side of the main gate. One was a demilitarized Lancaster heavy (four engine) bomber, and the other was a 22,000 pound (10 ton) "Grand Slam" bomb that was believed to be demilitarized. But it wasn't. This was first suspected when the crane, brought in to lift the shell of the Grand Slam onto a truck, could not get the bomb to move. It was too heavy. This Grand Slam wasn't just a shell. At first, officers thought it was filled with concrete. But that didn't really make much sense, and one pessimistic officer suspected that the bomb was still full of the original explosives. The local military bomb disposal team was called in, and they carefully checked. Turned out that this 13 year old, ten ton bomb was still full of explosives.
The bomb disposal team immediately ordered everyone within a 16 kilometer radius evacuated. That included the entire base, and the northern part of the nearby city of Lincoln. Bomb experts calculated that if the bomb had gone off, the base wound have been destroyed, along with the northern portion of Lincoln (including the 13th century Lincoln Cathedral). A larger crane, and sturdier tractor trailer, was quickly brought in, and the bomb was slowly, under a large police escort, moved to a coastal military test range. There the bomb was detonated (there being no other safe way to dispose of it.) The bomb proved to have lost none of its power, and thus Lincoln Cathedral was saved.
American "gate guards" and other memorials, suspected of possibly containing explosives, have the bomb disposal experts are called in to double-check. In the case of the British Grand Slam, no records could be found, from 1946, to explain how a live, ten ton bomb, was placed at the main gate as a memorial to the Lancaster bombers that dropped these weapons on Nazi targets. It's suspected that someone, at the time, realized the error, panicked, and destroyed the records. Then again, the bomb may have been moved innocently (someone assuming it was a dummy, filled with concrete), and the records lost, along with so many other contemporary paperwork of that sort.
In any event, errors like this still happen. A few years ago, air force munitions handlers loaded some cruise missiles on a B-52, to move the weapons to another base, without realizing that the missiles had nuclear, not dummy, warheads attached.
So, when moving old war memorials, if it's a bomb or shell, check to make sure it is a dummy, and not live, and very dangerous (as explosives become more unstable as they age).