The first batch of Diadems were powered by a pair of four-cylinder triple-expansion steam engines, each driving one shaft, which were designed to produce a total of 16,500 indicated horsepower (12,300 kW) and a maximum speed of 20.5 knots (38.0 km/h; 23.6 mph) using steam provided by 30 Belleville boilers.

They carried a maximum of 1,900 long tons (1,930 t) of coal[3] and their hulls were sheathed with copper to reduce biofouling.

[5] Andromeda was the fifth ship of her name to serve in the Royal Navy[9] and was laid down on 2 December 1895 by Pembroke Dockyard.

[11] In March 1901 the ship was one of two cruisers tasked to escort the ocean liner HMS Ophir, commissioned as a royal yacht for the World tour of the Duke and Duchess of Cornwall and York (later King George V and Queen Mary), from Gibraltar to Malta, and then to Port Said.

[12] Captain Christopher Cradock was appointed in command on 24 March 1902,[13] and from 11 June that year Andromeda served as flagship of the Cruiser Division of the Mediterranean Fleet.

[14] In May 1902 she visited Palermo to attend festivities in connection with the opening of an Agricultural Exhibition by King Victor Emmanuel,[15] and the following month the ship was in Gibraltar for a coronation fête.

[17] She returned home later that year and paid off at Portsmouth on 10 February 1903,[18] then transferred to the dockyard for a lengthy refit.

[9] She was later renamed Impregnable II in November 1919 and finally, HMS Defiance on 20 January 1931,[9] when she became part of the torpedo school.