On 28 March 1806 a ship flying the Russian navy’s St Andrew’s Cross limped into San Francisco harbour. Ignoring warning shots from a fort on the promontory, it dropped anchor, and a boat put ashore a tall, gaunt man wearing jewelled decorations over a baggy uniform spotted with mould. Washed and fed by the settlement’s Spanish governor, the strange visitor quickly recovered his poise. Within a fortnight he had not only betrothed himself to the governor’s 15-year-old daughter, but hatched plans to grab California for the tsar. The story of the expedition and of how close Russia came to extending its American colonies south to the Mexican border are the subjects of this rich, fascinating and thoroughly enjoyable book.

As Owen Matthews explains, Russia’s expansion eastward towards the Pacific had begun two centuries earlier, when teams of trappers started crossing the Urals in search of fur, especially sable. Soldiers followed, their wooden blockhouses gradually turning into settlements, and in 1633 a Cossack adventurer called Ivan Moskvitin became the first Russian to set eyes on the Pacific. A second fur-rush followed, fuelled by the coast’s vast colonies of sea-otters, and by the end of the 18th century half a dozen provisioning and warehousing bases had sprung up in Kamchatka, Alaska and on the islands in between, from which priceless loads travelled back overland across Siberia to market.

For Nikolai Rezanov, the scurvy-ridden Russian who rowed ashore at San Francisco, these dots on the right-hand side of the map were a long way from home. Born into the minor St Petersburg nobility in 1763, he showed no great early flair. A brief spell in the Guards was followed by four years as a provincial magistrate, then by another four in safe but dull posts at the Treasury and Navy Board. His first big gamble, at the age of 29, was to leave government service for the louche entourage of Platon Zubov, a favourite of Catherine II. Twenty-two years old to Catherine’s sixty-two (‘I am doing the Empire a great favour’, she quipped, ‘by educating the young’), Zubov was adored by the empress – who showered him with land and titles – but loathed by everyone else. Zubov’s unpopularity notwithstanding, the connection gave Rezanov an entrée into court, where he began building patronage networks of his own. The next turn in his fortunes came in 1794, when Zubov sent him to Irkutsk to oversee investments in a fur-trading venture owned by the Shelikhovs, the wealthiest of Siberia’s new rich merchant clans. There Rezanov quickly wooed and won a 14-year-old daughter of the house, gaining noble status (a distinct legal category) for her family, and a fortune for himself.

Back in St Petersburg, Rezanov began thinking big. His piratical father-in-law had already established fur-trading stations on the Aleutians, Kodiak Island and Sitka Sound (massacring indigenous peoples in the process). Given the same sort of royal patronage enjoyed by the East India and Hudson’s Bay Companies, the Shelikhov family firm could form the basis of a new Russian Pacific empire. Maritime trade, Rezanov assured the empress, might flourish as far afield as Shanghai and Bengal, and the double-headed eagle fly above Hawaii and Sakhalin. Thrown temporarily into jeopardy by Catherine’s death and Zubov’s fall in 1796, Rezanov’s lobbying eventually bore fruit, and the Shelikhov businesses re-emerged as the Russian American Company, with a trading monopoly, powers to maintain armies and dispense justice, and a new tsar, Alexander I, at the head of a distinguished list of shareholders. To mark her new ambitions, Russia would also launch her first round-the-world naval expedition, carrying scientists and artists, as well as an embassy, headed by Rezanov, to the secretive court of Japan.

Two ships, the Nadezhda and the Neva, set sail from St Petersburg in July 1803. On board the Nadezhda, team spirit was lacking from the start, thanks to a growing feud between Rezanov and her Baltic-German captain, Adam Johann von Krusenstern – both of whom, Matthews speculates, had been told they were in overall charge. Seasick, grieving for his young wife (newly dead in childbirth) and out of his depth among the professional naval men, Rezanov lost his usual power to please, turning ‘thoughtless, mean, partial and roaring’. On reaching Brazil, he used his run ashore to send the first of what was to become a stream of increasingly unhinged denunciations back to St Petersburg. Meanwhile Krusenstern erected a partition down the middle of the ship’s great cabin, creating one room for himself and his officers and another for the ambassador.

The Nadezhda spent the winter of 1804–5 anchored in Nagasaki Bay, as Rezanov tried to open negotiations for a trade agreement with the Shogunate. Confined to the ship and a small fenced compound, he made things harder for himself by pissing overboard in full view of boatfuls of interested Japanese and by refusing to make the proper obeisances to local officials. ‘I myself cannot understand’, one of the established Dutch traders who interpreted for him acidly remarked, ‘in what this self-abasement consists … in whatever part of the world one finds oneself one has to adapt or agree to the reigning customs and ceremonies. Otherwise, one need not go there at all.’ Six months on, an exquisitely polite letter arrived from the Shogun, categorically refusing all trade, and returning the mish-mash of palace lumber – vases, chandeliers, a clock in the shape of an elephant – that the Russians had brought halfway round the world as gifts. ‘All we have learned of Japan’, concluded the Nadezhda’s frustrated naturalist, ‘is through the telescope.’

Transferring – to everyone’s relief – to a Russian American Company brig, Rezanov spent the next year sailing the Bering Sea, inspecting Company outposts. On the Pribilov Islands he was told of mighty seal culls – 30,000 animals killed in a single day. On the Aleutians, he arrested a Russian official for mistreating the natives: the colonists, his doctor wrote, were ‘rascals’, by whom the Aleuts were ‘oppressed, tormented and plundered in every way’. On Kodiak Island he deposited a galvanic machine and a random collection of second-hand books in a log hut, announcing the opening of a new branch of the Academy of Sciences. In August he finally landed on the American mainland at Sitka Sound (in present-day southern Alaska). Circled by impenetrable, moss-muffled rainforest, its guns pointing inland at the warlike Tlingit tribes, Sitka did not feel like the birthplace of an empire. But while his officers boozed and brawled, Rezanov sat in a leaky, bark-roofed shack, penning more descriptions of a great Kamchatkan whale fishery, and of cargoes of furs, tea and American manufactures criss-crossing to Batavia, India and Tonkin. Reality closed in with winter and a growing shortage of food. Sick of sea-lion meat and cuttlefish, in February he bought a visiting Rhode Island trader, the Juno, and sailed south, washing up at San Francisco 34 days later.

Though no more than a cluster of adobe buildings, the Spanish settlement seemed like paradise to the exhausted Russians – blessedly ‘peaceful and ordered and sunny and un-tragic’. Back on dry land and astonishingly well fed – with fresh beef, salad, honey cakes and ‘super-excellent’ hot chocolate – Rezanov was finally able to bring his diplomatic skills to bear. The governor, José Dario Arguello, was swept off his feet – and even more so his beautiful daughter Conchita, to whom Rezanov became formally betrothed just two weeks after his arrival. It was, as Matthews says, quite a coup – in a fortnight Rezanov had gone from being an ‘overdressed stranger with bad breath’ to a confidant of the local ruling family, privy to government correspondence and secrets.

While flattering the local Franciscans and talking trade with delegates from Monterrey, he all the while took careful note of the Spanish defences. California, he concluded in letters to Tsar Alexander I later, was rich and ripe for the taking. If Russia did not make a move quickly, Britain or the United States would do so first. Fearing that Don José might receive orders to seize the Juno, Rezanov sailed away again on 10 May, promising to return for his bride. It was not to be: travelling home through Siberia he caught pneumonia and died in Krasnoyarsk, aged 43.

When the news reached St Petersburg Rezanov was hailed as a hero, his failed embassy to Japan and mad letters denunciating Krusenstern conveniently forgotten. Popular memory turned him into a figure of tragic romance, Conchita playing her part by remaining unwed and ending her days in a nunnery. Meanwhile his imperial visions faded. Distracted by the Napoleonic wars, Alexander never made a push for California. The Russian American Company stagnated: profits fell as sea-otters were hunted out, and liberal reforms Rezanov suggested in his final report home – that settlers be given land, and native trappers be paid in money instead of coupons redeemable only at Company stores – were never adopted. In 1867 the whole territory was sold, for two cents per acre, to the United States.

A century and a half later, Owen Matthews – himself half-Russian, and a veteran of the Moscow press corps – attended Sitka’s annual pageant marking the handover. Atop a replica wooden fort, historical re-enactors lowered Russia’s double-headed eagle and raised the Stars and Stripes. Sarah Palin made a speech, dressed in a North Face anorak against the driving rain. The crowd sang ‘The Star-Spangled Banner’ before processing, accompanied by fire trucks and a high school band, past St Michael’s Cathedral. To this day, the majority of native Alaskans are Orthodox. ‘That,’ Matthews concludes, ‘and chronic alcoholism, are the two most visible legacies of Russian America.’