Japan started the war being prepared to it earnestly. Japan received a generous economical and military help from the USA, England and Germany. In 1904 Russia was practically in a political isolation. Its ally France (in 1899 a change of letters between the ministry of external affairs of Russia and France confirmed the political agreement of 1891 and the army convention of 1893) announced its neutrality in the Far East conflict. The German government was interested in the provocative contradictions between Russia and Japan to redraw powers of Russia from the frontiers and provide its back in case of the war with France.
The Russian Empire was not ready to the war not only in the diplomatic meaning but also in the military one. In fact of the evident possibility of war with Japan, the concentration of the contingents in the Far East was going very slowly, the program of construction of vessels for the Pacific fleet was not fulfilled, the level of equipment of the army and navy was insufficient (new weapons were not so much). In January 1904 Japanese army was larger that that of Russia three times as many, in artillery (8 times) and in the number of warships (1.3 time). Apart from it the General Staff of the tsarist army was badly prepared to command, and among the high dignitaries flourished corruption and embezzlement of public funds.
The plan of the Japanese command assumed establishment of the domination on the sea to maintain the transport of the armies to the continent. The course on blocking and destruction of the Pacific squadron based in Port-Arthur in this connection was chosen. On the night of January 27 (February 9) 1904 a group of Japanese torpedo btorpedo boats suddenly attacked Russian warships. However Japanese did not manage to destroy and even to block the Russian fleet. Vice-admiral S.O.Makarov, who headed the Pacific squadron on the 24th of February, the talented naval commander; native of sailor's family; he took measures to activate actions of the squadron. In result Japanese could not land on the Lyaodun peninsula. But on the 31st of March the battleship 'Petropavlovsk' was blown up on a mine and sank, Makarov, officers of the staff and 620 sailors died. The new commander of the squadron, V.K.Witheft refused to do offensive actions and escaped in Port-Arthur, and Japanese immediately began to manoeuvre to the continent.
Already in the first battle on the Russian land the Russian forces were defeated: in the middle of April on the river Yalu the 1st Japanese army of 45 thousand soldiers forced the 8th thousand Eastern group of general M.I.Zasulich to retreat in disorder to Lyaoyan. On the 22nd of April on the Lyaodun peninsula began to land the 2nd Japanese army of the general Oku, composed of about 50 thousand soldiers, that jeopardized Port-Arthur. The 4th army of general Nodzu landed at Dagushan.
To the summer of 1904, Port-Arthur was already thoroughly fortified, its garrison made up 42 thousand soldiers, the squadron - 12 thousand sailors. General R.I.Kondratenko played an outstanding role in the defense of Port-Arthur. In August the Japanese command made attempt to seize Port-Arthur, having thrown in the assault its 45th thousand army. From the 6st to the 11th of August defenders of the fortress was beating off attacks of the enemy that had significant advantage in artillery. Having lost almost 25 thousand soldiers Japanese were compelled to proceed to the systematic siege of the fortresses.
The defeat near Port-Arthur forced Japanese commander-in-chief Oyama to attack on the Russian Manchurian army by the 1st, 2nd and 5th armies, trying to surround and destroy Russian armies near Lyaoyan. There were 148 thousand Russian bayonets and 673 pieces of ordnance. Japanese had 110 thousand bayonets and 484 guns. The battle near Lyaoyan began on the 17th of August, and in the evening commanders of the 2nd and the 4th Japanese armies declared the impossibility to continue the attack because of enormous casualties. By the 21st of August the Japanese armies, which lost over 24 thousand soldiers and ran out of shells and foodstuffs, were ready to retreat. But Êuropatkin, ignorant of the position of the opponent and a little panic-stricken by the events, in the morning of the 21st of August gave the order to retreat to Mukden. Russian casualties near Lyaoyan were almost 17 thousand soldiers.
In September 1904, the number of soldiers of the Russian army in Manchuria reached 210 thousand. Forces of Japanese were held down near Port-Arthur distracting no less than half of the Japanese reserves, artillery and shells. In this conditions Êuropatkin, at last dared to take the initiative and in September 1904 attacked on the river Shakhe, in a mountainous insufficiently studied district. After several unsuccessful attacks of Russian armies Kuropatkin took on the defensive. Both parties with huge casualties for three months have been at the trench war, which was called 'Shakhe sitting".
After three unsuccessful attacks of Port-Arthur (in August, September and in the middle of October), having huge casualties, Japanese turned to the mine and artillery war, and on the 13th of November more than 100 thousand soldiers started the fourth storm. Having captured Vysokaya Mountain, the enemy began by aimed fire to destroy ships of the Russian squadron. Defenders of the fortress held the line with their last ounce, headed by the talented generals R.I.Kondratenko and general Smirnov.
On the 20th of December 1904 the act of surrender of Port-Arthur was signed. The Russian fleet was destroyed, and 32 thousands soldiers, including ill and wounded, were captured.
In 1905 on the Far East there were two largest battles in the history of wars: the Ìukden battle on land and Tsusima battle at sea. Actions near Mukden lasted from the 5th till the 24th of February 1905; they involved more than 660 thousand soldiers from both sides. The battle ended by retreat of the Russian army during which they suffered heavy casualty. A part of the army was boxed in. Casualty of Japanese were 70 thousand people, 52 thousand were wounded and 22 thousand soldiers were captured.
In May 1905, in the zone arrived the 2nd and the 3rd Pacific squadrons with the tsarist government's task "to seize the sea of Japan". Against 30 Russian warships Japan put 120 repaired and perfectly equipped ships. At equal number of battleships the Japanese fleet in 6 times surpassed the Russian one in a number of cruisers and torpedo boats. The Pacific squadrons accepted the battle on the 14th and the 15th of May 1905 near the Island of Tsusima. The Japanese ships fired point-blank at the Russian battleships. On the 14th of May 11 Russian ships, including 5 battleships were lost. Rozhdestvensky was contused, admiral Nebogatov actually did not control the battle. Torpedo attacks destroyed 2 more battleships. Some ships were sunk by own crews not to surrender them to the enemy. Only a small group leaded by Nebogatov gave themselves up on the 15th of May being surrendered. In total sank 19 warships, 3 cruisers cut their way to neutral ports, 2 cruisers and 2 torpedo boats reached Vladivostok. Of 14 thousand seamen, 5 thousand were died and the same number were captured. The route of the Russian navy was complete.
Despite of operations favorable for Japan, its exhaustion of material and manpower resources forced the Japanese government to search for the peace with Russia. The peace conference took place on the 27th of July (9th of August) 1905 in Portsmouth (USA). After long diplomatic struggle of the Russian delegation led by Vitte it became possible to reject the requirement of Japan for payment of the huge contribution, extradition of the Russian warships that took cover in neutral ports, restriction of the Russian Navy on the Far East. Japan could not achieve the seizure of Southern Sakhalin occupied in June 1905. Russia rent Japan Lyaodun peninsula with Port-Arthur and Dalny, "ceded" to the Japanese government the southern part of Sakhalin and nearest islands, and also the branch line from Port-Arthur to Changchun.
The Portsmouth peace treaty was signed on the 23rd of August (5th September) 1905.