Top Secret Exchange: The Tizzard Mission and the Scientific War

Dean F. Oliver is a postdoctoral fellow at the Norman Paterson School of
International Affairs.

Zimmerman argues that the top secret scientific mission to the United
States and Canada led by Sir Henry Tizard in the fall of 1940 was vital
to the Allied war effort, though it was not viewed with such unbridled
enthusiasm at the time. The notion that Britain ought to provide
classified information to the still-neutral Americans was highly
controversial, Zimmerman notes, with Winston Churchill an outspoken
skeptic. Believing strongly that American secrets were an open book to
German intelligence, many influential Britons also doubted whether
American know-how could much improve the Commonwealth’s war-fighting
ability. Operating on a strict quid-pro-quo basis, London ignored the
possible long-term effects of scientific free trade. Military events in
1940 helped force Churchill’s hand, but the valuable initiative
remained in doubt until Tizard’s departure for North America in
August.

Describing these developments, mostly from the British perspective,
occupies the first half of the book; tracing the mission’s impact
fills the second. The wide-ranging contacts benefited all participants,
Zimmerman argues. Of even greater significance were the habits of trust
and understanding that the visit helped forge, ties that had a
“profound psychological impact” and “stripped away any pretence of
petty nationalistic security concerns which would otherwise have impeded
the free and open exchange of information.”

There are minor weaknesses in the later chapters. Some of Zimmerman’s
assertions regarding the mission’s broader significance will not bear
close scrutiny (the exuberant quotation at the close of the previous
paragraph is a prime example), while Tizard’s return to England midway
through the mandate is never satisfactorily explained. This portion of
the book also assumes a somewhat immodest tone in its critique of
existing scholarship, culminating in an extraordinary endnote (number
11, page 230) in which Zimmer-man chastises as “incompetent” several
historians for recommending that one of his earlier articles not be
published.

Quibbles aside, Top Secret Exchange is an important book—well
documented, ably written, and handsomely produced. It will be of great
interest to World War II scholars and to historians of science on both
sides of the Atlantic.