The novel Blue at the Mizzen forms the last completed work in Patrick O'Brian's Aubrey-Maturin series. A blue ensign at the mizzen-mast indicated the presence of a Rear Admiral of the Blue, the lowest flag-rank in the Royal Navy of the early 19th century.

Plot summary

Jack Aubrey and Stephen Maturin again sail into the South Pacific on a secret mission: this time to help the Chileans secure independence from Spain.

After the end of the Napoleonic Wars, the Surprise makes her way out of Gibraltar but collides heavily with a Nordic timber ship and has to return for repairs. In the meantime, Aubrey conducts a clandestine affair with his cousin Isobel, Lord Barmouth's new young wife. Admiral Lord Barmouth hastens the repair work, having at first delayed it by giving preference to Royal Navy ships. The frigate makes her way to Madeira for more serious repairs but arrives just in time to see Coelho's famous yard at Funchal in flames. Maturin receives a coded report from Dr Amos Jacob regarding the Chilean situation and takes the Ringle to England, where Sir Joseph Blaine updates him — the Chileans have split into two factions (northern and southern), with the southerners retaining the services of Sir David Lindsay to command the Chilean navy. Whilst Stephen stays with Sophie Aubrey at Woolcombe, Jack returns the Surprise to Seppings' yard in England for a thorough re-fit and also recruits a strong competent crew out of Shelmerston for the long voyage ahead.

In London, the Duke of Clarence asks Aubrey to accept his illegitimate son Horatio Hanson (whom the Duke refers to as a former shipmate's son, for propriety's sake) as a midshipman. Initially reluctant, Aubrey finds to his surprise and delight that the boy has the mathematical skills essential for a navigator; and he becomes a competent sailor.

After leaving England, the Surprise first heads for Sierra Leone in order that Maturin can make a proposal of marriage to a young attractive widow living in Freetown. Christine Wood shares his tastes for natural philosophy and appears altogether more level-headed than his late wife Diana. Whilst she attracts him physically, so that he has erotic dreams about her, she has suffered from her previous marriage to an impotent husband. Initially unwilling to marry him, she does consent to visit the Aubreys at their home in Dorset and to meet Maturin's daughter Brigid there.

After a difficult rounding of Cape Horn, the expedition reaches San Patricio in Chile, a storage post for whalers. Ringle has to go to a yard for repairs following a grounding in the Pillón passage. After a meeting between Aubrey and Maturin and Sir David Lindsay, in which the two sides agree to mutually support each other, Maturin writes a letter to Blaine describing the different juntas and the training of three republican sloops by the Surprises, who assist in capturing a moderate privateer. After meeting Dr Jacob once more, Aubrey decides to make his way with the Surprise and Ringle to Valparaiso and Maturin and Jacob ride there by mule. Here they meet General Bernardo O'Higgins (the Supreme Director), and General Eduardo Valdes (a cousin of Maturin's). Learning that the Peruvian viceroy of the Spanish king plans to invade Chile, the group determine to confront the Royalist forces at Valdivia, where the viceroy will need to seek stores. After dinner aboard, the Surprise and Ringle make sail and Aubrey elaborates a plan to drop Chilean troops at Concepcion while the ships destroy the gun-emplacements at Cala Alta and then bombard the fort at Valdivia.

The plan succeeds and the revolutionaries capture four chests of silver and one of gold, conveyed by the Surprise to Valparaiso and then overland to Santiago. Sir David Lindsay fights a duel with one of his officers and dies. Popular local sentiment gradually turns against the British, and Aubrey receives news that the local junta at Villanueva plans to impound his frigate. He decides on a bold action to cut out the Peruvian fifty-gun frigate Esmeralda from Callao to strengthen the Chilean navy. Assisted by the Ringle, Surprise conducts a hard-fought broadside action and eventually the British-Chilean force takes the ship, although Aubrey suffers wounds in the thigh and chest. Maturin and Jacob compose a coded message to Sir Joseph Blaine which the schooner takes to the Lisbon packet for delivery via Panama and a returning merchantman.

The President of the Valparaiso junta, Don Miguel Carrera, gives Aubrey and his officers a lavish dinner, after which Aubrey insists on his sailors receiving their share of the prize-money and Esmeralda's value. The next day he receives a note from Don Miguel confirming the delivery of five thousand pieces of eight and use of any naval stores the Surprise requires. With a happy and fully re-equipped ship, Aubrey sets about exercising the young Chilean naval officers as his frigate continues her survey. Finally, Amos Jacob arrives on a green brig with a coded message from Sir Joseph Blaine: the Duke of Clarence requests Horatio Hanson's return to sit his lieutenant's examination (after having fought very valiantly in the cutting-out episode) but, more importantly, the Admiralty requires Aubrey to take command of the South African squadron, hoisting his flag at the River Plate, blue at the mizzen, aboard HMS Implacable.

Characters in Blue at the Mizzen

• Jack Aubrey - Post-Captain; promoted to a Rear Admiral of the Blue
• Stephen Maturin - ship's surgeon, friend to Jack and an intelligence officer
• Sophie Aubrey - Jack's wife
• Christine Wood - Stephen's latest love-interest
• Dr Amos Jacob - assistant surgeon and intelligence officer
• Prince William, the Duke of Clarence
• Horatio Hanson - the Duke's bastard son; later master's mate on the Surprise
• Mr Harding - First Lieutenant on the Surprise
• Mr Oates - Second Lieutenant on the Surprise
• Mr Whewell - Third Lieutenant on the Surprise
• Mr Woodbine - master on the Surprise
• Preserved Killick - Aubrey's steward
• Grimble - Killick's mate
• Awkward Davies - long-serving Able Seaman
• Joe Plaice - long-serving Able Seaman
• Poll Skeeping - loblolly boy
• Mr Wells - midshipman on the Surprise
• Mr Adams - Captain Aubrey's secretary
• William Reade - commander of the Ringle
• Mr Wantage - master's mate
• Mr Daniel - master's mate
• Latham - Jack's new coxswain
• Padeen Colman - Maturin's servant
• Sir Joseph Blaine - Head of Intelligence, Admiralty
• Sarah and Emily Sweeting - Stephen's god-daughters, with Mrs Broad at the Grapes
• Brigid Maturin - Stephen Maturin's daughter
• Charlotte, Fanny, Philip and George Aubrey
• Colonel Roche - Wellington's aide-de-camp at Waterloo
• Lord Barmouth - Commander-in-Chief of Mediterranean Fleet
• Lady Barmouth
• Lord Keith - retired admiral
• Lady Keith
• Mr Wilkins - Delaware's Master
• Clarissa Andrews (formerly Clarissa Oakes) - married to the rector of Wytherton

Chile:

• Sir David Lindsay - ex Post-Captain in the Royal Navy; ex-officio commander of the Chilean navy
• Don Bernardo O'Higgins - Supreme Director of Chilean revolutionaries
• General Eduardo Valdes - General in the Chilean revolutionary army
• Don Miguel Carrera - President of the local junta in Valparaiso

Ships in Blue at the Mizzen

• HM hired hydrographical vessel Surprise - twenty-eight gun frigate (with a 36-gun frigate's main mast)
• HMS Ringle - Surprise's escort
• the Asp - ex-Royal Navy; being re-fitted in Chile
• USS Delaware - Captain Lodge
• Isaac Newton - a converted packet ("the Lisbon packet"); carrying some Members of the Royal Society
• O'Higgins - ancient heavy frigate ex Spanish navy (name afterwards changed to San Martin)

Allusions/references to actual history, geography and current science

History

The main plot loosely echoes Lord Cochrane's setting up and commanding the Chilean Navy from 1818 to the early 1820s. A historical figure from Chile's independence movement, Don Bernardo O'Higgins, also features in the book.

Natural history

Whilst in Sierra Leone, Christine Wood shows Stephen Maturin a prodigious amount of wildlife, including:

• an elephantine heron (Ardea goliath)
• a nightjar with elongated flight feathers (Shaw's Caprimulgus longipennis)
• a feather from the Congo peacock

Coca leaves

In Peru, Maturin and Jacob also have a discussion about coca-leaves - Maturin keeps his leaves in his inner pocket in a pouch, along with the lime and necessary outer wrapping. Maturin expresses curiosity about their use in considerable quantities, and the resultant reaction according to altitude. He cites the porters in the Peruvian Andes, who increase their dose if they have to carry a heavy burden over a very high pass.

Jacob mentions that many sorts of coca exist — for example, the Tia Juana; and that asthmatic patients and those afflicted by migraines often experience hallucinations, their strength and frequency varying with the height.

Reviews

"Filled with exuberance and humor, and a writer's palpable delight at exercising his finest muscles. . . . At sea with a master." — San Francisco Chronicle

"O'Brian has presented his readers with a shining jewel...an intricate, multifaceted work." — The New York Times Book Review

Editions

• W.W. Norton & Company; Paperback Reprint edition (1999) (ISBN 0393048446)
• Recorded Books, LLC; Unabridged Audio edition narrated by Patrick Tull (ISBN 1402591748)