Pfc. Sebastian Rodriguez, machine gunner, Weapons Platoon, Lima Company, 3rd Battalion, 3rd Marine Regiment, Marine Rotational Force – Darwin, fires an M240 machine gun during a night squad-attack exercise, here, May 22, 2013. (Photo by Sgt. Sarah Fiocco/U.S. Marines)

Russian soldiers write home while serving on the Eastern Front during World War I, circa 1915. (Photo by Hulton Archive/Getty Images)

Fans of the Brazilian heavy metal band Sepultura enjoy their showo at the main stage of Rock in Rio festival 2019 at the Olympic Park, Rio de Janeiro, Brazil, on October 4, 2019. The week-long Rock in Rio festival started September 27, with international stars as headliners, over 700,000 spectators and social actions including the preservation of the Amazon. (Photo by Mauro Pimentel/AFP Photo)

In this image provided by Maine State Police, emergency crews work to remove a tractor-trailer hauling 15 million bees to be used in pollinating the state's blueberry crops after it overturned on Interstate-95, Thursday evening, May 10, 2024, in Clinton, Maine. The driver was taken to a hospital and most of the bees were contained, officials said. (Photo by Maine State Police via AP Photo)

“Dover Castle is a medieval castle in the town of the same name in the English county of Kent. It was founded in the 12th century and has been described as the “Key to England” due to its defensive significance throughout history. It is the largest castle in England.

The outbreak of the Second World War in 1939 saw the tunnels converted first into an air-raid shelter and then later into a military command centre and underground hospital. In May 1940, Admiral Sir Bertram Ramsey directed the evacuation of French and British soldiers from Dunkirk, code-named Operation Dynamo, from his headquarters in the cliff tunnels”. – Wikipedia

Photo: The Repeater Station in the subterranean tunnels underneath Dover Castle, which has been restored by English Heritage for a public exhibition on June 3, 2011 in Dover, England. The evacuation of allied soldiers from Dunkirk was masterminded and co-ordinated from the secret command and control centre in the tunnels deep below the castle. (Photo by Matthew Lloyd/Getty Images)