The third film to feature Laurence Olivier and Vivien Leigh - previously castmates in Fire Over England (1937) and 21 Days Together (1940) (also Alexander Korda productions) - "That Hamilton Woman" would be the only film the couple made during their marriage. In fact Olivier and Leigh had been contracted for "Hamilton Woman" while Leigh's divorce from Leigh Holman was still pending: Leigh and Olivier would marry August 28 1940 - three days after Leigh's divorce was finalized. Their honeymoon - on Ronald Colman's yacht off Catalina Island no more than 50 miles from Hollywood - was necessarily brief as "Hamilton Woman" had already begun production.
Nelson's eye wound was the result of a cannon shot he received at the Siege of Calvi in 1793, when he was a Captain. Upon disembarking with his men, a projectile fell next to him, spraying sand and gravel in his left eye, which was permanently blinded. His other eye was also affected, so he often wore a visor to protect it from direct sunlight, never actually wearing an eye patch, despite popular imagery. In fact, during the Battle of Cape St. Vincent, Nelson disobeyed an order to retreat with his division by putting the spyglass to his blind eye and pretending he did not see the signals.
The newly-married Leigh and Olivier had recently lost a great deal of their own money on a disastrous production of "Romeo and Juliet" touring the US. Their salaries enabled them to return to Britain, and a bonus for Leigh enabled her to send her mother and six-year old daughter to Canada, away from the impending bombing.
The story was meant to draw a clear parallel between the threats posed by Napoleon in the film and Hitler in reality.