The 'Nerobefehl' was the German order issued by Adolf Hitler that the German forces, when forced to retreat, were first to destroy everything that might be of use to the forces driving them back into the heartland of Germany (19 March 1945/8 May 1945).
The order was only very seldom obeyed, largely because the retreating German forces often lacked the time and/or explosives to undertake such demolitions, and because they were unwilling to destroy infrastructure within Germany.