河内は、イギリス海軍のドレッドノートに対抗すべく、日本が独自に建造した初のド級戦艦であり、初めて保有した2万t越えの戦艦です。30.5㎝連装砲6基を搭載し、カーチス式直結型タービンを導入した有力な新鋭戦艦として期待されていました。しかし、主砲配置が保守的な亀甲型だった上、主砲が異口径（前後2基が50口径、中央4基が45口径）ゆえに射撃管制を統一できないという難点を抱えていました。
内は、就役後は主力艦隊に配備され、第一次世界大戦時には膠州湾封鎖作戦などに参加しました。大正7（1918）年7月12日徳山湾に停泊中に突如大爆発、わずか４分で沈没着底しました。総員1,020名のうち621名の乗員が退艦の猶予もなく殉難したと言われています。就役から僅か6年の短い生涯でした。

Battleship HIJMS Kawachi
The Kawachi, which was designed to counter the HMS Dreadnought, was the first Dreadnought class ship designed and built in Japan, and the first to surpass 20,000 tons. With twelve 12-inch guns and the installation of Curtis directly-coupled turbines, she was expected to be a powerful cutting-edge battleship. However, her main guns were laid out in a turtle shell arrangement, in six twin turrets: one forward, one aft, two to starboard, and two to port. Her guns were of different calibers, (the forward and aft turrets were of 50 caliber, the central turrets 45 caliber), making it very difficult to coordinate fire. After commissioning, the Kawachi was deployed as a main line battleship, and participated in the Siege of Tsingtao in the First World War. On July 12, Taisho 7 (1918), while anchored in Tokuyama Bay she suffered a sudden explosion and sank in a mere four minutes. Of 1,020 crew on board, 621 could not evacuate in time and perished. From her commissioning to her loss she had a short service life of only six years.