Seventy-nine years ago today, 20 July 1944, Colonel Count Claus von Stauffenberg, a much-wounded young Wehrmacht officer, packed a briefcase in a broiling Berlin and flew to the ‘Wolf’s Lair’ the headquarters of Adolf Hitler deep in a Polish forest 100 miles behind the eastern front.

Stauffenberg – who had lost an eye, a hand, and all but two fingers on his remaining hand in North Africa – packed a deadly load wrapped in a spare shirt: two lumps of captured British-made plastic explosives along with their detonators.