Foreign aggression from so many quarters called forth a patriotic movement in China, which in 1900 culminated in the "Boxer" revolt. For a while Japan and the European Powers, including Russia, became allies, to save their embassies and repress the rising about Pekin. In the campaign the Japanese forces proved themselves the most efficient of all, and their chiefs returned home with an absolute confidence that they could successfully meet European soldiers in the field.

Japan had made the most unsparing use of its rights in Korea, acquired by the Treaty of Shimonoseki, all but absolutely annexing the country. After the Boxer revolt Admiral Alexieff, who was governor of the Russian possessions in the Far East, embarked on a dangerous policy of provocation towards Japan. He had an ill-informed contempt for the hardy islanders. He underrated their power of resistance, and felt sure that the mere fact that the Russian fleet outnumbered theirs would secure the command of the sea for Russia, and have a decisive effect in the event of a conflict. He believed that the sooner it came the better.

The Russian fleet in the East was steadily reinforced, unit by unit. The Japanese people began to see in these proceedings, and in the work done at Port Arthur, a threat of early hostilities, and there was a general call on the Government to anticipate the blow, when relations became strained between the two countries in 1903. The Tokio Government was anxious not to precipitate the war, for the organization of the army required some months for completion, but the feeling in the navy, army, and civil population forced its hand. After a brief delay of negotiations, during which both parties worked with feverish energy to secure additional armaments, diplomatic relations were broken off at the beginning of February, 1904, and then, without waiting for any formal declaration of war, the Japanese torpedo flotilla swooped down on the Russian fleet lying in the roads outside the narrow entrance of Port Arthur, found them utterly unprepared to meet this sudden attack, and crippled several of the ships. A second blow was the destruction of the first-class armoured cruiser "Variag," the Russian guardship at Chemulpo, by a Japanese squadron.

Most of the best ships in the Russian navy were in the East at the outbreak of the war. Alexieff had, however, made the initial mistake of dividing the force at his disposal. Away north at Vladivostock was a squadron of three large armoured cruisers, the "Gromoboi," "Rossia," and "Rurik," and the protected cruiser "Bogatyr." The "Variag" was isolated at Chemulpo, the port of Seoul, doing duty that might have been left to a gunboat. At Port Arthur, under Admiral Stark, there was a strong fleet, including seven battleships, the "Petropavlosk," "Poltava," "Peresviet," "Pobieda," "Retsivan," "Sebastopol," and "Tsarevitch," the cruisers "Askold," "Boyarin," "Bayan," "Pallada," "Diana," and "Novik," and a flotilla of torpedo craft and the mine-laying steamer "Yenessei." In the torpedo attack on the evening of 8 February the "Retsivan," "Tsarevitch," and "Pallada" were badly damaged. The "Variag" was destroyed next day, and a few days later the "Yenessei" accidentally blew herself up while laying mines. This series of disasters seemed for a while to have almost destroyed the morale of the fleet. Stark set to work to repair his damaged ships, made no attempt to meet the Japanese at sea, or interfere with the transport of their armies to the mainland of Asia, and, subordinating his fleet to the defence of Port Arthur, even landed guns and men to strengthen the landward works. The Japanese blockaded the port, insulted it with long-range bombardments, and tried to block the narrow entrance by sinking old steamers across it.

In March the arrival of the best officer in the Russian Navy, Admiral Makharoff, for a while inspired new energy into the Port Arthur fleet. The repairs of the injured ships were completed, and on 13 April the admiral steamed out to challenge Togo and the main Japanese fleet to battle. Notwithstanding precautions taken against the known danger of floating mines, the fleet entered a tract of water where several were afloat, and the flagship "Petropavlosk" was destroyed with fearful suddenness by the explosion of one of them. There was great loss of life, but the most serious blow to Russia was the death of the admiral.

After the fleet returned to the harbour there came another period of irresolute inactivity. It was not till August, when several ships had been injured at their anchors by the bombardment from the land batteries of the Japanese attack, and it was evident that the port would soon be a dangerous place for the ships, that Admiral Witjeft proceeded to sea, announcing that he was going to Vladivostock, the cruiser squadron from that port having been warned to come out and reinforce him on his way.

The sea-fight, known as the battle of the Tenth of August, took place a few miles to seaward of the port. Witjeft led the fleet in his flagship the "Tsarevitch," followed by the battleships "Retsivan," "Sebastopol," "Pobieda," "Poltava," and "Peresviet" (carrying the flag of the second in command, Rear-Admiral Prince Ukhtomsky), and the cruiser division made up of the "Askold" (carrying the flag of Rear-Admiral Reitzenstein), "Pallada," "Diana," and "Novik," besides eight destroyers. The cruiser "Bayan" had been so damaged that she was left in port. Witjeft had a marked superiority in battleships. Togo had had six new first-rate ships of the class under his command at the outset of the war, but on 15 May he had lost two of them, one-third of his battleship fleet, by a disaster like that of the "Petropavlosk." On that May morning, while cruising off Port Arthur, he ran into a field of drift mines, and in a few minutes the battleships "Hatsuse" and "Yashima," and the cruiser "Yoshino," were destroyed. The Japanese managed till the end of the war to conceal the fact that the "Yashima" had been lost, and the Russians up to the battle of Tsu-shima believed Togo had five of his big battleships intact. In the battle of 10 August he put in his main fighting-line the two powerful armoured cruisers "Nisshin" and "Kasuga," purchased from the Argentine Government on the eve of the war.

The battle began with long-range firing at 1 p.m., and continued till after seven in the evening. It was decided by the superior gunnery of the Japanese, and the damage done by their high explosive shells. The "Tsarevitch," badly cut up and set on fire, was driven out of the line. Witjeft was killed by a shell. His last word was to reiterate his order to push for Vladivostock. As darkness came on Ukhtomsky lost heart, and led the fleet back to Port Arthur. If he had held on he might have got through the Japanese fleet, for their ammunition was almost exhausted when the firing ceased. Reitzenstein, with the cruisers, tried to execute Witjeft's last order. The "Pallada," however, left him and followed the battleships. The rest of the cruiser squadron and the destroyers that accompanied it were forced to part company, and only the "Novik" got through to the northwards. The "Diana" fled southwards to the French port of Saigon; the "Askold," with a destroyer, reached Shanghai. The battered "Tsarevitch," with three destroyers, took refuge at Kiao-chau. All these ships were disarmed by the French, German, and Chinese authorities, and detained till the end of the war, when they were restored to the Russian Government.

The "Novik" failed to get into Vladivostock, but reached a Russian port in Saghalien, where a few days later she was tracked down and destroyed by Japanese cruisers. The Vladivostock squadron had come out to meet the unfortunate Witjeft. The "Boyarin" was left behind, damaged by accidentally grounding, so the squadron was made up of the three big armoured cruisers "Gromoboi," "Rossia," and "Rurik." They were approaching the straits of Tsu-shima, and were as far south as Fusan, when they were discovered and attacked by Admiral Kamimura's cruiser squadron, on 14 August. Once more good gunnery against poor shooting decided the fight. The "Rurik" was sunk, and the "Gromoboi" and "Rossia" returned to Vladivostock, bearing marks of very hard hitting—riddled funnels, and sides hastily patched with plates of iron, told of the straight shooting of the Japanese cruisers. In both the action with the Port Arthur battleship fleet and the Vladivostock cruiser squadron the losses of the Japanese had been very slight.