Mikasa, named after Mount Mikasa, was laid down by Vickers at their Barrow-in-Furness shipyard on 24 January 1899.
She was launched on 8 November 1900 and completed on 1 March 1902.
After a visit to Devonport, she left Plymouth on 13 March 1902, bound for Yokohama, under the command of Captain Hayasaki.

At the start of the Russo-Japanese War, Mikasa, commanded by Captain Hikojirō Ijichi, was assigned to the 1st Division of the 1st Fleet.
She participated in the Battle of Port Arthur on 9 February 1904 when Admiral Tōgō Heihachirō led the 1st Fleet in an attack on the Russian ships of the Pacific Squadron anchored just outside Port Arthur.
Tōgō had expected his surprise night attack on the Russians by his destroyers to be much more successful than it actually was and expected to find them badly disorganized and weakened, but the Russians had recovered from their surprise and were ready for his attack.
The Japanese ships were spotted by the cruiser Boyarin which was patrolling offshore and alerted the Russian defences.
Tōgō chose to attack the Russian coastal defences with his main armament and engage the Russian ships with his secondary guns.
Splitting his fire proved to be a bad idea as the Japanese 8-inch (203 mm) and six-inch guns inflicted very little significant damage on the Russian ships who concentrated all their fire on the Japanese ships with some effect.
Although a large number of ships on both sides were hit, Russian casualties numbered only 17 while the Japanese suffered 60 killed and wounded before Tōgō disengaged.
Mikasa was hit by two ten-inch shells during the engagement that wounded seven crewmen.

The ship participated in the action of 13 April when Tōgō successfully lured out a portion of the Pacific Squadron, including Vice Admiral Stepan Makarov's flagship, the battleship Petropavlovsk.
When Makarov spotted the five battleships of the 1st Division, he turned back for Port Arthur and Petropavlovsk struck a minefield laid by the Japanese the previous night.
The Russian battleship sank in less than two minutes after one of her magazines exploded, and Makarov was one of the 677 killed.
Emboldened by his success, Tōgō resumed long-range bombardment missions, which prompted the Russians to lay more minefields which sank two Japanese battleships the following month.

During the Battle of the Yellow Sea on 10 August, Mikasa was at the head of the column of Japanese battleships and was one of the primary targets of the Russian ships.
She was hit twenty times, two of which knocked out her aft 12-inch gun turret, and suffered 125 casualties among her crew.
In turn, she concentrated most of her fire upon the battleships Poltava and Tsesarevich although both ships were only lightly damaged by the Japanese shells which generally failed to penetrate any armour and detonated on impact.
Mikasa, named after Mount Mikasa, was laid down by Vickers at their Barrow-in-Furness shipyard on 24 January 1899. She was launched on 8 November 1900 and completed on 1 March 1902. After a visit to Devonport, she left Plymouth on 13 March 1902, bound for Yokohama, under the command of Captain Hayasaki.
At the start of the Russo-Japanese War, Mikasa, commanded by Captain Hikojirō Ijichi, was assigned to the 1st Division of the 1st Fleet. She participated in the Battle of Port Arthur on 9 February 1904 when Admiral Tōgō Heihachirō led the 1st Fleet in an attack on the Russian ships of the Pacific Squadron anchored just outside Port Arthur. Tōgō had expected his surprise night attack on the Russians by his destroyers to be much more successful than it actually was and expected to find them badly disorganized and weakened, but the Russians had recovered from their surprise and were ready for his attack. The Japanese ships were spotted by the cruiser Boyarin which was patrolling offshore and alerted the Russian defences. Tōgō chose to attack the Russian coastal defences with his main armament and engage the Russian ships with his secondary guns. Splitting his fire proved to be a bad idea as the Japanese 8-inch (203 mm) and six-inch guns inflicted very little significant damage on the Russian ships who concentrated all their fire on the Japanese ships with some effect. Although a large number of ships on both sides were hit, Russian casualties numbered only 17 while the Japanese suffered 60 killed and wounded before Tōgō disengaged. Mikasa was hit by two ten-inch shells during the engagement that wounded seven crewmen.
The ship participated in the action of 13 April when Tōgō successfully lured out a portion of the Pacific Squadron, including Vice Admiral Stepan Makarov's flagship, the battleship Petropavlovsk. When Makarov spotted the five battleships of the 1st Division, he turned back for Port Arthur and Petropavlovsk struck a minefield laid by the Japanese the previous night. The Russian battleship sank in less than two minutes after one of her magazines exploded, and Makarov was one of the 677 killed. Emboldened by his success, Tōgō resumed long-range bombardment missions, which prompted the Russians to lay more minefields which sank two Japanese battleships the following month.
During the Battle of the Yellow Sea on 10 August, Mikasa was at the head of the column of Japanese battleships and was one of the primary targets of the Russian ships. She was hit twenty times, two of which knocked out her aft 12-inch gun turret, and suffered 125 casualties among her crew. In turn, she concentrated most of her fire upon the battleships Poltava and Tsesarevich although both ships were only lightly damaged by the Japanese shells which generally failed to penetrate any armour and detonated on impact.
Japanese battleship Mikasa