https://www.rmg.co.uk/stories/blog/curatorial/rum-deal-origins-nelsons-blood

Legend has it that Pusser’s Rum is sometimes referred to as ‘Nelson’s Blood’, because after the great Admiral Nelson’s death at the Battle of Trafalgar in 1805, in which his body was preserved in a cask of spirits, holes were drilled into the sides and the liquid drained. Sailors essentially drank his blood during the long journey.

https://www.rmg.co.uk/stories/blog/curatorial/rum-deal-origins-nelsons-blood