She was purpose built to support 12 of the new 'D' Class submarines under the 1910/11 Naval Programme.

[1] Maidstone commissioned at Portsmouth on 15 October 1912, as the principal depot ship of the officer commanding the newly established 8th Submarine Flotilla.

This was the offensive submarine force based in UK waters.

[3] Maidstone led the 8th Submarine Flotilla to its war station at Harwich in the 1914 mobilisation.

She remained the principal depot ship for the offensive submarine force at Harwich for the duration of the hostilities.