Corbin Williamson’s thesis examines the repairs performed on Royal Navy warships in American shipyards prior to U.S. entry into World War II. Under the auspices of the Lend-Lease Act of March 1941, 37 British warships were repaired or refitted in the United States by the end of the year. By examining the diplomatic and political context for the decision to repair these ships as well as the organization, implementation, and impact of these repairs, two arguments are tentatively advanced. First, that this example of early Anglo-American cooperation demonstrates that the U.S. was purposefully involved in an undeclared naval war with the European Axis in the summer of 1941. Second, that these repairs significantly and materially aided the Royal Navy in fulfilling its wartime responsibilities during a critical period of the war at sea.