The British Admiralty ordered 20 Acorn-class destroyers as part of the 1909–1910 shipbuilding programme for the Royal Navy.

[1] Three of the class, Alarm, Acorn and Brisk, were to be built by the Clydebank shipbuilder John Brown and Company.

[5] She was one of seven destroyers that suffered problems when steaming at full speed off the coast of Ireland during the 1911 Naval Manoeuvres, with serious leaks of water through hull rivets into the ships' oil tanks, requiring that they put into Portland Harbour for repairs.

[8] On the outbreak of the First World War, the 2nd Destroyer Flotilla, including Alarm joined the newly established Grand Fleet at Scapa Flow.

[9][10] On 16 October 1914, four destroyers of the 2nd Flotilla, Lyra, Nymphe, Nemesis and Alarm were patrolling at the eastern end of the Pentland Firth between Orkney and mainland Scotland.

[15] On 24 March 1917, Alarm picked up 11 survivors from the merchant ship Achille Adam, sunk the previous day by the submarine UB-39 when bound for Newhaven from Saint-Valery-sur-Somme.

In response, the unknown ships, which were actually the Austro-Hungarian destroyers Triglav, Uzsok, Dukla, Lika and Csepel, opened fire.

Both Hornet and Jackal were damaged in the exchange of fire, but the Austro-Hungarian ships abandoned their raid as the alarm had been raised.

Alarm, Cimeterre, Comet and Torrens responded to the gunfire, and joining up with Jackal chased after the Austro-Hungarian ships, but broke off the pursuit as they approached the enemy coast, owing to the risk from mines.