The film was a critical and financial success, and while on the surface the plot is both a war story and a romance set in Napoleonic times, it was also intended to function as a deliberately pro-British film that would portray Britain positively within the context of World War II which was being fought at that time. At the time the film was released France, Belgium, the Netherlands, Norway, Poland and Denmark had all surrendered to the Nazis and the Soviet Union was still officially allied to them, correspondingly the British were fighting against the Nazis alone and felt the need to produce films that would both boost their own morale, and also portray them sympathetically to the foreign world, and in particular, to the United States. …
Shot in the United States during September and October 1940,[10] That Hamilton Woman defines Britain’s struggle against Napoleon in terms of resistance to a dictator who seeks to dominate the world.[11] The film was intended to parallel the current situation in Europe and was intended as propaganda at a time before the attack on Pearl Harbor when the United States was still formally neutral. … Stars Vivien Leigh and Laurence Olivier were newlyweds at the time of filming and were considered a “dream couple.” …
While That Hamilton Woman was marketed as historical romance, its subtext falls into the “war propaganda” category.[16] In July 1941, the isolationist group America First Committee (AFC) targeted That Hamilton Woman and three other major Hollywood feature films (The Great Dictator, Chaplin/United Artists, 1940; Foreign Correspondent, Wanger/United Artists, 1940; The Mortal Storm, MGM, 1940) as productions that “seemed to be preparing Americans for war.” …
Critical sources usually point out that That Hamilton Woman was Winston Churchill’s favorite film.[19][Note 1] In her research on the subject, film historian Professor Stacey Olster reveals that at the time the film was made, Alexander Korda’s New York offices were “supplying cover to MI-5 agents gathering intelligence on both German activities in the United States and isolationist sentiments among makers of American foreign policy.”[20] According to Anthony Holden, Olivier’s biographer, That Hamilton Woman “became Exhibit A in a case brought against Korda by the Senate Foreign Relations Committee. The Committee had accused him of operating an espionage and propaganda center for Britain in the United States—a charge Korda only escaped by virtue of the fact that his scheduled appearance before the committee on December 12, 1941 was preempted by the Japanese bombing of Pearl Harbor five days earlier”.
The New York Times review is mixed, but this stood out:
Nelson is made to appear the great and important man that he was, with some especially timely opinions about dictators who would desire to invade England and “tear down that which other men have built up.”