Two empires, one Manchuria
Meiji Japan’s crash modernisation had produced a first-rank army and navy and a great power’s appetites; Tsarist Russia was building the Trans-Siberian railway toward the Pacific and leasing from enfeebled China the naval base Japan had been forced to hand back a decade earlier: Port Arthur. When negotiations over Manchuria and Korea stalled — St Petersburg, expecting nothing from “an infantile nation,” barely negotiated — Japan opened the war in February 1904 with a night torpedo attack on the Port Arthur squadron before the declaration arrived: a precedent noted, in Washington among other places, for later reference.
The fighting
The war’s texture was the 20th century arriving early: trench lines, machine guns, barbed wire, heavy artillery with indirect fire, minefields sinking battleships — the full Western Front kit, ten years ahead of schedule, observed by foreign attachés who filed reports their own armies then largely ignored. The siege of Port Arthur consumed six months and tens of thousands of lives (General Nogi’s human-wave assaults on 203 Metre Hill became bywords); Mukden (February-March 1905) pitted over 600,000 men — the largest battle fought anywhere to that date; and the naval decision came at Tsushima on 27-28 May 1905, where Admiral Togo — crossing the T with the signal “the Empire’s fate depends on this one battle” — met Russia’s Baltic Fleet at the end of its epic 18,000-mile voyage (begun by shelling British fishing boats at Dogger Bank under the impression they were Japanese torpedo craft) and annihilated it: of 38 Russian ships, nearly all were sunk or taken, against Japanese losses of three torpedo boats — the most one-sided decisive fleet action of the modern era.
Portsmouth and the ripples
Both empires were exhausted — Japan financially, Russia politically, with Bloody Sunday and the 1905 Revolution (the battleship Potemkin mutinying mid-war) burning behind the front. US President Theodore Roosevelt brokered the Treaty of Portsmouth (September 1905), earning the first American Nobel Peace Prize; Japan took Port Arthur, the Korean protectorate (annexation followed in 1910), and half of Sakhalin — but no indemnity, provoking riots in Tokyo from a public told less about the war’s true costs (perhaps 130,000-170,000 dead in all) than its victories.
The deepest effects were psychological. For Russia, humiliation and revolution rehearsed 1917; for Japan, confirmation as a great power on a trajectory that ran, ultimately, to 1941 — the pre-declaration torpedo attack included. And across the colonised world — in Indian, Vietnamese, Persian, Ottoman, and pan-African writing of the day — Tsushima landed like Adwa at fleet scale: proof, celebrated from Calcutta to Cairo, that European supremacy was a condition, not a law.