[1][a] They were designed at the start of the First World War as relatively fast minesweepers that could also carry out various miscellaneous duties in support of the fleet such as acting as dispatch vessels or carrying out towing operations, but as the war continued and the threat from German submarines grew, became increasingly involved in anti-submarine duties.

[1] Snowdrop was ordered on 4 May 1915 from the Scottish shipbuilder Archibald McMillan & Son, and was built at their Dumbarton shipyard as Yard number 463.

[4][7][8] Snowdrop joined the 1st Sloop Flotilla, operating under the Vice Admiral Commanding, Coast of Ireland, following commissioning.

[13] On 5 April 1917, the merchant ship SS Canadian, which had been torpedoed by U-60 the previous day, sank 25 nmi (29 mi; 46 km) west of Bantry Bay.

The British submarine H5 drove off U-50 and later that day, Snowdrop took Dykland under tow at a speed of only 1.5 knots (2.8 km/h; 1.7 mph), attempting to bring the damaged ship back to Bantry Bay.