This patriotic tune was written in 1759 by David Garrick, the most famous English actor of his day. The song, set to William Boyce's music, remains the official march of the Royal Navy of the United Kingdom, the Royal Canadian Navy, and the Royal New Zealand Navy. It was originally written for an opera that debuted on New Years Eve in 1760.
The oak in the song's title refers to the best wood used in constructing British warships during the age of sail. The "heart" is the strongest central wood of the tree.
The song makes an appearance in Star Trek: The Next Generation, Season 3, Episode 18, where Captain Picard uncharacteristically toasts the crew with the first verse.