Lieutenant and Commander B. A. Austen was appointed in command of the
Stag on 14 February 1902, and commissioned her at
Chatham on 25 February for service with the Instructional Flotilla. Only weeks later, Lieutenant John Maxwell D. E. Warren was appointed in command from 18 March 1902. In May 1902 she transferred her officers and crew to
HMS Sturgeon. She was commissioned at
Chatham on 2 September 1902 by Commander
Sir Douglas Egremont Robert Brownrigg for outbound journey to the Mediterranean, where she was placed in the fleet reserve at
Malta. Her crew returned home, while Brownrigg succeeded in command of
HMS Coquette,
tender to
HMS Orion,
depot ship for destroyers on the
Mediterranean Station. On the night of 22 November 1910,
Stag collided with the destroyer , with both destroyers suffering damaged
stems. The cruisers and went to the assistance of the two damaged destroyers, which were taken into
Syracuse, Sicily for repair. She remained with the Mediterranean Fleet until 1913. On 30 August 1912 the Admiralty directed all destroyers were to be grouped into classes designated by letters based on contract speed and appearance. As a two-funnelled destroyer with a contract speed of 30 knots,
Stag was assigned to the . The class letters were painted on the hull below the bridge area and on a funnel. In February 1913,
Stag was still listed as a part of the Mediterranean Fleet, but by April it was reported that she, along with , and were to be laid up at Malta, to await new crews to be sent from
Devonport. Stag left Malta in November 1911 and arrived at Plymouth on 1 December that year. On her return to the UK she joined the
6th Destroyer Flotilla, a patrol flotilla based at
Devonport. These patrols, manned with nucleus crews only in peacetime, would have the wartime duty of defence of the East Coast, patrolling to prevent hostile ships from approaching the coast without being detected and attacked, and defence of ports against enemy raids. In January,
Stag transferred to the
8th Destroyer Flotilla, another patrol flotilla based at
Chatham. ==World War I==