When the Soviet Union was invaded in 1941, the authorities quickly decided to move their factories east across the Urals in anticipation of the Blitzkrieg. This saved a lot of production capacity and helped win the war.
I don't know whose idea it was or how it was conceived, because as far as I know, this is the only mass migration of factories in the history of war.
So I'm here to ask if that's really true. Is there any other instance of major migration of factories in any other war, before or since?