HMS Diadem was the lead ship of the Diadem-class

Diadem class cruiser

The Diadem class cruiser was a class of "First-Class" protected cruiser built for the Royal Navy during the 1890s that served in the First World War...

 of protected cruiser

Protected cruiser

The protected cruiser is a type of naval cruiser of the late 19th century, so known because its armoured deck offered protection for vital machine spaces from shrapnel caused by exploding shells above...

 in the Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

. She was built at Fairfield Shipbuilding & Engineering Co Ltd, Govan

Govan

Govan is a district and former burgh now part of southwest City of Glasgow, Scotland. It is situated west of Glasgow city centre, on the south bank of the River Clyde, opposite the mouth of the River Kelvin and the district of Partick....

 and launched on 21 October 1896. She served in the First World War with her sisters. In 1914 she was a stokers' training ship, and was placed in reserve in October 1915. She was returned to being a stokers' training ship in January 1918, and survived the War to be sold to Ward of Morecambe for breaking up on 9 May 1921.