Seven years earlier, in the same bay they were leaving, Commodore Perry's (ペリー, Perī) black ships had arrived in Uraga (浦賀) and forced Japan open at gunpoint. Now, in February 1860, Japan was sailing out.

The Kanrinmaru (咸臨丸) was a Dutch-built steam corvette, ordered in 1853 — the same year Perry arrived — as Japan's first attempt to construct a modern navy from almost nothing. She was small, she was barely suited for open-ocean passage, and the men aboard her had trained for harbor navigation, not the North Pacific in winter. Of 96 Japanese crew, only one had ever sailed out of sight of land before.

The official mission was diplomatic: the Kanrinmaru was to escort the first Japanese embassy to the United States, traveling separately aboard the USS Powhatan, which would ratify the Harris Treaty (日米修好通商条約, Nichi-Bei Shūkō Tsūshō Jōyaku) — the formal trade and diplomatic agreement with America. Japan needed to show it could operate Western-style warships. The voyage was as much symbol as mission.

Captain Katsu Kaishū (勝海舟) was exactly the kind of man the moment required: a low-ranking Tokugawa samurai who had taught himself naval strategy from Dutch texts, a visionary who understood that Japan's only path forward was transformation. He also got terrible seasick. Within the first week at sea, as the Kanrinmaru drove northwest and then east across the North Pacific in the teeth of winter storms, Katsu was largely confined to his cabin.

The storms that hit the crossing were, in the words of a seasoned officer aboard the USS Powhatan escort, 'the worst ever encountered in the Pacific.' Lt. John M. Brooke, USN, who had been assigned to sail alongside the Japanese crew in an advisory capacity, stepped into a de facto command role during the worst of the weather. His journal records a mixture of alarm and frustration: the Japanese officers, trained in sheltered harbor work, had little idea what to do when waves were running higher than the ship's deck.

The man who bridged the gap was not a trained officer at all. John Manjirō (ジョン万次郎, Jon Manjirō), born in 1827 in Tosa Province, had been a teenage fisherman when a storm wrecked his boat and left him stranded on an uninhabited island. An American whaling ship rescued him. His captain brought him to Massachusetts, where he learned English, studied navigation, and absorbed the rhythms of open-ocean seamanship. He eventually returned to Japan, where his unusual biography made him invaluable as a translator and cultural interpreter. On the Kanrinmaru, when the Pacific tried to kill them, Manjirō's American education kept the ship pointed east.

Thirty-seven days after leaving Uraga (浦賀), the Kanrinmaru passed through the Golden Gate and anchored in San Francisco Bay. The date was March 17, 1860. The crossing was complete — barely, imperfectly, but complete.

San Francisco received them with astonishment and warmth. The crew was celebrated, entertained, and observed with intense curiosity. Katsu Kaishū, recovered enough to walk the city, looked at the wharves, the warehouses, the factories, and the organized machinery of American commerce, and felt something close to dread. He had not understood, until he saw it with his own eyes, how vast the distance was between what Japan had and what the industrialized West possessed. He came home convinced that Japan had perhaps a decade before it would be absorbed or destroyed unless it modernized at any cost.

But the most consequential thing that happened in San Francisco that month was quieter than Katsu's strategic alarm.

Fukuzawa Yukichi (福澤諭吉), 25 years old, had come aboard as personal steward to the titular captain Kimura Yoshitake (木村喜毅). His real interest was observation. In the streets of San Francisco, he walked and looked and asked questions, mentally calculating the prices of sugar and cloth and comparing them with Japanese equivalents, trying to quantify the economic gap. In a bookshop, he found a Webster's Dictionary.

He bought it. He brought it home. He published Japan's first English-Japanese dictionary. Then he did not stop. He went on to write the essays that gave Meiji Japan its vocabulary for concepts like 'freedom,' 'independence,' and 'civilization.' He founded Keio University, one of Japan's great institutions. He became, by most measures, the most influential intellectual of the Meiji era — the man who translated the modern world into terms Japanese readers could absorb and act on. Today his face is on the 10,000-yen note.

Katsu Kaishū (勝海舟) returned from the voyage and spent the next decade building Japan's first modern naval academy. In 1868, when the Boshin War (戊辰戦争, Boshin Sensō) brought imperial forces to the gates of Edo, it was Katsu — the samurai who had crossed the Pacific and understood what modernization required — who negotiated the bloodless surrender of Edo Castle with Saigō Takamori (西郷隆盛), saving the city from destruction and enabling the Meiji Restoration to proceed without a burning capital.

The Kanrinmaru herself ended less gloriously. She ran aground and sank in Hokkaido (北海道) in 1871. But a monument now stands at Lincoln Park in San Francisco, overlooking the Golden Gate Bridge — a gift from the mayor of Osaka in 1960, on the centennial of the crossing — honoring the ship and the men who sailed her into the world that was coming for them whether they were ready or not.

They weren't entirely ready. But they crossed anyway.