- "If I am not back aboard the Lydia within one hour, she'll train her guns upon your fort and reduce it to rubble."
"With you in it, Captain?"
"That is my order."
- ―Horatio Hornblower and El Supremo[src]
The Lydia was a middle-sized fifth-rate built at Woolwich in 1796 to the design of Sir William Rule at a cost of £19,070. Her commission under Hornblower began on March 12th, 1807. She sailed first to Alexandria, Egypt, but then in 1808 was given secret orders for a very ambitious mission to Central America. There, the 36-gun Lydia fought and sank the much larger Spanish ship of 50 guns, the Natividad.
Lydia supported a crew of 274 and was armed with twenty-six 18lb guns, eight 9lb guns, and two 12lb guns. She was 143 feet long and berthed 951 tons.
- Horatio Hornblower, Captain
- William Bush, First Lieutenant
- Gerard, Second Lieutenant
- Donald Galbraith, Third Lieutenant
- Rayner, Fourth Lieutenant
- Clay, Midshipmen
- Hooker, Midshipman
- Lady Barbara Wellesley, sister of the Duke of Wellington seeking passage from Panama back to England
- Hebe, Lady Barbara's handmaid
- Samuel Simmonds, Lieutenant of the Marines
- Bailey, Gunroom Steward
- Benskin, Seaman
- Brown, Captain's Coxswain
- Chump the Negro, Seaman
- James Clifton, Boatswain's Mate
- Crystal, Master
- Dawson, Seaman
- Gray, Master's Mate
- Hall, Ordinary Seaman
- Hankey, Ship's Surgeon
- Harrison, Boatswain
- Harper, Ordinary Seaman
- Hudson, Ordinary Seaman
- Laurie, Acting Surgeon, Purser's Steward
- Owen, Seaman
- Polwheal, Captain's Steward