On 25 August 1939, nine days before France declared war on Germany, the staff of the Louvre began history’s greatest museum evacuation. The artworks went first to the châteaux of the Loire valley, then moved on to escape the advancing Nazis – Mona Lisa made six nail-biting journeys to new hide-outs. Here, Gerri Chanel tells the story of the curators’ battles to save the Louvre collections, from the first exodus to the homecoming in the summer of 1945.