Queen Elizabeth had reportedly planned to whack Idi Amin over the head with a ceremonial pearl sword if he "gatecrashed" a Silver Jubilee church service in 1977.
The British monarch had told her cousin Lord Mountbatten of her plan ahead of the service to celebrate her 25 years on the throne at St Paul's Cathedral, News.com.au reported.
The story, which was discovered in Lord Mountbatten's diary by the historian Prof. Philip Murphy, shows her concern about the ruthless dictator's attendance at the event.
Amin was known to have murdered his enemies and presided over a brutal regime in Uganda until his overthrow in 1979.
