 Just before the invasions, the records and papers of Frédéric Joliot, Hans Halban and Lew Kowarski were smuggled out of France, and eventually to England.Included in this operation were 26 drums of heavy water, the world’s entire stock at the time.Some of the papers written by Halban and Kowarski were deposited at the Royal Society in the UK, where they were sealed with a note from James Chadwick, dated December 18, 1941, that said, “The paper is such that it would be inadvisable to publish it at the present time.” The papers described the outline of a design for a nuclear fission reactor.