Blue at the Mizzen is the twentieth and last completed historical novel in the Aubrey-Maturin series by Patrick O'Brian, first published in 1999. It is set after the Napoleonic wars, in the fight for Chilean independence from Spain.

Jack Aubrey and Stephen Maturin, having heard the details of Napoleon's defeat at Waterloo and having collected their share of the prize from their last capture, set sail for the dual mission of charting the Chilean coast and aiding those who seek independence from Spain. Maturin and his colleague Dr Amos Jacob speed the plot as covert intelligence agents and Aubrey's political advisors, while Aubrey makes bold moves in dealing with the factions in Chile.

Reviewers were positive about this novel, finding it "a shining jewel", "an intricate, multifaceted work -- one of those rare novels that actually bear up under close scrutiny." The "deeper sense of the culture of the age" that marks the series is also true of this novel, which shows the "period of deflation, both economic and emotional" for the Royal Navy and its associated businesses after the victory. The new midshipman introduced in this novel, and Maturin's new love, are well-liked. The young man is "a dashing young foil for the ship's elders", who shows that the main characters have aged and their pace has changed. The voyage to Chile treats readers once again "to O'Brian's talent for life on board, incidents and accidents". Aubrey has earned a "just reward" at the end, made an admiral of the blue. Feelings about the series as a whole are also positive, and strongly stated: ""There is nothing in this century that rivals Patrick O'Brian's achievement in his chosen genre."; and readers can so easily enter this fictional world, because "O'Brian did the hard learning long ago and then began to write with fully justified assurance and pleasure."

Plot summary

The Surprise sails out of Gibraltar but collides in the dark with a Nordic timber ship and returns for repairs. Back ashore, Aubrey hears a reliable description of the battle at Waterloo; he thanks Lord Keith for moving the prize court along briskly to share out their huge prize from capturing the gold meant to aid Napoleon before his fall, more than 382 pounds a share. Aubrey has clandestine visits with his cousin Isobel, Lord Barmouth's wife. Admiral Lord Barmouth hastens the repair work, realizing he helps himself that way. Many Surprises desert. The frigate sails to Madeira for more serious repairs but arrives just in time to see Coelho's famous shipyard 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 still interested in British help, and southern retaining the services of Sir David Lindsay to command the Chilean navy. Whilst Maturin stays with Sophie Aubrey at Woolcombe, Aubrey returns the Surprise to Seppings' yard in England for a thorough re-fit and recruits a strong, competent crew out of Shelmerston for the long voyage ahead. In London, the Duke of Clarence asks Aubrey to accept Horatio Hanson as a midshipman. Initially reluctant, Aubrey finds that the boy has the mathematical skills essential for a navigator and he becomes a competent sailor. Fully fitted, the Surprise stops at Funchal, picking up Jacob, and then heads for Freetown, where Maturin proposes marriage to a young attractive widow named Christine Wood. She shares his tastes for natural philosophy, but her view of marriage suffered from her first marriage, as her husband was impotent and she turns him down. She agrees on her upcoming trip to England to visit the Aubreys at their home in Dorset and to meet Maturin's daughter Brigid there. Surprise then sails to the coast of Brazil, where Dr Amos Jacob parts to cross the mountains overland.

After a difficult rounding of Cape Horn, the expedition reaches San Patricio in Chile. Ringle goes for repairs following a grounding in the Pillón passage. After a meeting between Aubrey, Maturin and Sir David Lindsay, in which the two sides agree to mutually support each other, Maturin writes to Blaine describing the different juntas and the training of three republican sloops by the crew of the Surprise, who assist in capturing a moderate privateer. After meeting Dr Jacob with the intelligence he gathered, Aubrey heads to Valparaiso, while Maturin and Jacob ride there by mule. Here they meet General Bernardo O'Higgins, the Supreme Director, and Colonel Eduardo Valdes. Learning that the viceroy of Peru, under 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. The Surprise and Ringle make sail and Aubrey elaborates a plan to drop Chilean troops at Concepción 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 fights a duel with one of his officers and dies. Popular local sentiment gradually turns against the British, and Aubrey receives news that the junta plans to impound his frigate. He decides to pre-empt action against Surprise by cutting out the Peruvian fifty-gun frigate Esmeralda at Callao in Peru to strengthen the Chilean navy. Surprise conducts a hard-fought broadside action and eventually the British-Chilean force takes the ship. Aubrey suffers wounds in the thigh and shoulder. Maturin and Jacob send a coded message of the successful cutting-out to Sir Joseph Blaine which the schooner takes to the Isaac Newton, as Dobson's friends agree to carry the message across Panama to meet a returning merchantman. Ringle carries the news to Valparaiso.

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 by the end of the month. The next day Don Miguel authorizes five thousand pieces of eight and use of any naval stores the Surprise requires. With a fully repaired ship, Aubrey sets about training the young Chilean naval officers as the Surprise continues her survey of the Chilean coast for several weeks. Jacob arrives from Valparaiso on a private brig, with coded messages from Sir Joseph Blaine. First, the Duke of Clarence requests Horatio Hanson's return to sit his lieutenant's examination. Second, the Admiralty promotes Aubrey to Rear Admiral of the Blue, requiring him to take command of the South African squadron aboard at the River Plate, hoisting his flag, blue at the mizzen. Carrera arrives with a message saying it will take a further three months to complete the payments, releasing Aubrey from his responsibility to the Chileans. Aubrey sets course for the Strait of Magellan.

Characters

Jack Aubrey: Post Captain of HMHV Surprise, promoted to a Rear Admiral of the Blue in the Royal Navy Stephen Maturin: Ship's surgeon, physician, natural philosopher, friend to Jack, widower, and intelligence agent Sophia Aubrey: Wife of Jack and mother of their three children. Charlotte and Fanny Aubrey: Twin daughters of Jack and Sophia Aubrey. George Aubrey: Son of John and Sophia Aubrey, now midshipman on HMS Lion with Captain Heneage Dundas. Philip Aubrey: Much younger half brother of Jack, midshipman in the Royal Navy. Brigid Maturin: Daughter of Stephen Maturin and his late wife Diana Villiers. Padeen Colman: Maturin's Irish servant, now part of his household on land. Sarah and Emily Sweeting: God-daughters of Maturin since he rescued them from a Melanesian island, who live with Mrs Broad at the Grapes. Introduced in The Nutmeg of Consolation. Mrs Clarissa Andrews: Wife of the rector of Wytherton, née Harvill. Widow of Lieutenant Oakes and once governess for Brigid Maturin, now living apart from the Maturin household. Introduced in Clarissa Oakes. John Leicester: Nephew to Attorney Lawrence, agricultural agent for the estate Aubrey inherited from cousin Edward, whose plan for the unproductive land has been successful, with tenants still in place, rents paid, and crops harvested. Christine Wood: Widow of Sierra Leone Governor, natural philosopher and now pursued by Maturin in Freetown.

In Gibraltar or aboard SurpriseColonel Roche: Wellington's aide-de-camp at Waterloo who dines with Royal Navy officers in Gibraltar. Lord Barmouth: Commander-in-Chief of Mediterranean Fleet. Lady Barmouth: His wife, and cousin to Jack Aubrey. Lord Keith: Retired admiral, good friend to Aubrey. Queeney, Lady Keith: Wife of Lord Keith and childhood friend of Jack Aubrey. Mr Harding: First Lieutenant on the Surprise. Mr Somers: Second Lieutenant on the Surprise. Mr Whewell: Third Lieutenant on the Surprise. Mr Woodbine: Master on the Surprise, old and experienced. He dies of unknown causes after the ship rounds Cape Horn. Mr John Daniel: Master's mate on Surprise, one who loves numbers and has strong navigational skills. Promoted to Sailing Master on the death of Mr Woodbine. Preserved Killick: Aubrey's steward who also tends to Maturin. Grimble: Killick's mate. Latham: Jack's new coxswain. Awkward Davies: Long-serving able seaman who befriends Hanson, and kills the man who wounded Aubrey in the leg in the action to cut out the Esmeralda. Joe Plaice: Long-serving able seaman. Mrs Poll Skeeping: Loblolly girl in the sick bay of Surprise. Mr Wells: Young midshipman on the Surprise, a first-voyager. Mr David Adams: Captain Aubrey's clerk, introduced in The Nutmeg of Consolation. Mr William Reade: Midshipman and master's mate, who is most often commander of the Ringle. He lost an arm in action, now using a hook; he was introduced in The Thirteen Gun Salute.

Met in Madeira Dr Amos Jacob: Assistant surgeon aboard Surprise, physician colleague of Maturin, linguist and intelligence officer. Mr Henry Wantage: Master's mate on Surprise, still at Madeira since he failed to come aboard at the end of The Yellow Admiral and invited to rejoin. Died of yellow fever after leaving Freetown.

Met in England Sir Joseph Blaine: Head of Intelligence at the Admiralty. William, Duke of Clarence: Younger brother to the Prince Regent and a sailor who rose to captain; he was once treated by Maturin and ever after his admirer. Mr Horatio Hanson: Duke's beloved illegitimate son, who knows the Duke as a friend of the family, taken aboard Surprise as a midshipman. Promoted to master's mate upon the death of Mr Wantage, ahead of Daniel due to long sea time on record. In the cutting-out expedition, he did well, coming after Davies to fight off those who would attack the fallen Aubrey.

Met in the doldrums Mr Lodge: Captain of USS Delaware, he met Aubrey in Boston (The Fortune of War). They meet again in the doldrums, Delaware having rounded Cape Horn. Mr Wilkins: Master of USS Delaware, who has two chronometers not matching, impairing navigation. Dr Evans: Surgeon aboard USS Delaware who knew Michael Herapath (Desolation Island and The Fortune of War) and his recent successes in medicine and Chinese poetry.

Met in Chile Austin Dobson: Entomologist and Fellow of the Royal Society who inherited a great sum; he used it to purchase the vessel that previously served as the "Lisbon packet", fitting it out for a scientific voyage with several other Fellows and renaming the vessel Isaac Newton. He is on the Chilean coast at the same time as the Surprise. Sir David Lindsay: Former Post-Captain in the Royal Navy, dismissed for calling his Admiral out to duel, and now ex officio commander of the Chilean navy, aligned with the groups in the south of Chile. He is quick to take offense and is killed in a duel with one of his officers. Don Bernardo O'Higgins: Supreme Director of Chilean revolutionaries, and supporter of Aubrey.