Six days before the declaration, Japan had already made its intentions clear.

On February 4, the imperial government decided for war. On February 6, Japan recalled its minister from St. Petersburg and severed diplomatic relations. On the night of February 8–9, the Imperial Navy's torpedo-boat destroyers glided through the darkness into Port Arthur harbor and struck Russia's Pacific fleet without warning. By the time Emperor Meiji signed the 宣戦布告 (sensen fukoku) — the formal declaration of war — on February 10, 1904, the fighting was already two days old and Japan had already drawn first blood.

The declaration's language was blunt and imperial: "We hereby declare war against Russia and We command Our Army and Navy to carry on hostilities against that Empire with all their strength." No hint in the text that the Navy had already been at war for forty-eight hours. No acknowledgment that the diplomatic sequence — sever relations, strike, then announce — had been carefully engineered. The declaration was signed in the Emperor's name, issued from the Imperial Palace in Tokyo, and sent to a watching world as a statement of sovereign intent.

But the Emperor, according to multiple sources, had not wanted to send it.

Meiji (明治天皇, Meiji Tennō) had reigned since 1867 and had spent his entire reign presiding over one of the most radical transformations any nation had ever attempted. In 1868, Japan was a feudal archipelago governed by 侍 (samurai) clans under a 将軍 (shōgun) whose line had held power for 265 years. By 1904, it had a conscript army modeled on Prussia's, a navy modeled on Britain's, a constitution, a parliament, railways, factories, and a national identity built from the careful fusion of 武士道 (bushidō) ethics and Western military science. The 侍 (samurai) class had been legally dissolved in the 1870s. The sword had been replaced by the rifle. The domain loyalty had been replaced by loyalty to the nation and the Emperor.

The Emperor reportedly said that if Japan lost, he did not know how he could apologize to his ancestors. The phrase is almost untranslatable in its cultural density. The word that carries it is 恩 (on) — obligation, debt, the weight of what one owes to those who came before. Even as the nominal head of a modern industrial state, Meiji framed the war in the language of ancestral duty. He was not afraid of Russia in any simple sense. He was afraid of having failed the dead.

The architects of the war had no such hesitation. A generation of Meiji-era military officers — men who had studied in Berlin and London, who had read Clausewitz and watched the Franco-Prussian War, who understood exactly what modern industrial warfare required — had concluded that Russia was not invincible, that Japan's window of advantage was narrow, and that waiting was more dangerous than striking. Japan had already defeated China in 1895 and won the Liaodong Peninsula, only to have Russia, Germany, and France force the peninsula back in the Triple Intervention. The humiliation had not been forgotten. This time, Japan would move first.

The fighting validated their calculations. Port Arthur fell in January 1905 after an eleven-month siege. The Battle of Mukden (奉天会戦, Hōten Kaisen) in March 1905 was the largest land battle in history to that point. And in May 1905, Admiral Tōgō Heihachirō (東郷平八郎) destroyed Russia's Baltic Fleet at the Battle of Tsushima (対馬海峡海戦, Tsushima Kaikyō Kaisen) — an engagement so one-sided it passed into naval legend. Of 38 Russian ships, 21 were sunk, 7 captured, 6 disarmed. Japan lost three torpedo boats.

The Treaty of Portsmouth (ポーツマス条約, Pōtsumasu Jōyaku), signed in September 1905 and brokered by U.S. President Theodore Roosevelt, gave Japan the Liaodong Peninsula, the South Manchurian Railway, the southern half of Sakhalin Island, and recognized Japan's dominance over Korea. It was the first time in the modern era that a non-European nation had defeated a major European power — in a sustained military campaign, on land and sea, from start to finish.

The shockwave traveled far. In India, in Egypt, in Turkey, in Finland, in Poland — in every nation that had been told, explicitly or implicitly, that European military power was simply beyond the reach of non-European peoples — Japan's victory was read as proof that the hierarchy was not fixed. Anti-colonial movements across Asia and Africa drew direct inspiration from it. Russia's defeat contributed to the Revolution of 1905. The world that had existed before February 10, 1904 did not reconstitute itself afterward.

For the arc of samurai history, the declaration is both an ending and a culmination. The system Minamoto no Yoritomo (源頼朝) had built in 1185 — warrior rule, discipline, the primacy of those who could fight — had been dismantled in 1868. The 侍 (samurai) class, legally speaking, no longer existed in 1904. But the ethos had not died. It had been absorbed, formalized, and pointed outward. The men who fought the Russo-Japanese War were not 侍 (samurai). They were conscripts and naval officers and general staff planners with European educations.

But the spirit encoded in those seven words — "with all their strength" — was unmistakably the same spirit that had animated Japanese warriors for seven hundred years. The 宣戦布告 (sensen fukoku) of February 10, 1904 was, among other things, the Meiji era's answer to a question that had hung in the air since 1868: had Japan kept what mattered when it threw away what didn't?

The answer came back from Tsushima in forty-five minutes of gunfire.