"Opal" was one of 25 destroyers (consisting of 22 M-class destroyers and three s) ordered in late November 1914 as part of the Third War Programme.The M class was the latest class of destroyers ordered for the Royal Navy before the outbreak of the First World War, and this order was one of a series of large orders for destroyers of this class placed in the early months of the war which resulted in 90 ships being ordered by May 1915 in addition to ships ordered prior to the outbreak of the war.