The Royal Navy began to pay attention to mine trawling after the Russo-Japanese War (1904-1905). The main reason for this was the ability of the Russians to efficiently use naval mines in defense against the Japanese fleet.

Due to the start of the First World War, the Admiralty decided to continue with the minesweeper project on September 25, 1914, but established new criteria for the design of the ships. The wartime required ships to perform different functions: mine dragging, anti-submarine operations, support convoys, tugboats, and organizing transportation. The need to perform various operational tasks influenced the design of the ships because the construction of the hull of a multi-purpose minesweeper had to be as simple as possible. This helped save a considerable amount of time for the construction of new ships, which was extremely valuable during the war. Another reason for making such a decision was that cargo steamer-like ships were unlikely to be taken as warships due to their shape and therefore the enemy might decide not to attack them. This in turn reduced the workload for shipyards specializing in military vessels, as the simple design of the ships meant that they could also be built in civilian shipyards.

As the intention was well to use minesweepers for transportation, they were built with large decks and closed railings. Only the dead weight of the deck was 50 tons, so it could be used to carry up to 700 soldiers. Flower-class ships even carried horses on their decks during the war. The simple design of the Flower-class ships meant that shipyards could build them quickly; typically, it took only 19 to 21 weeks to complete a vessel. The minesweeper Myrtle, which belonged to the Azalea subclass of the Flower class, was launched on October 11, 1915.

The British light cruiser squadron operated actively in the Baltic Sea during the Estonian War of Independence (1918-1920). They mainly helped the Estonian Republic to fight Soviet Russia and controlled the activities of German troops in the Baltic states.

Regardless of the heavy traffic in the Baltic Sea, it was the most heavily mined maritime area in the world. The Russian and German fleets dumped approximately 34,000 naval mines in Estonian waters alone during the First World War. During the War of Independence, only narrow passages had been traced through the minefields, so navigation in Estonian waters was only carried out under the direction of experienced captains. The British fleet wanted to clear mine crossings to develop cargo ship traffic and expand its own operations. On June 10, 1919, the Daphne, Gentian, Godetia, Lilac, Lupine and Myrtle from the first flotilla of minesweepers were sent to the Baltic Sea. Ordering them to clear the passes to the west of the islands of Saaremaa and Hiiumaa.

The minesweeper Myrtle sank during a mine clearance operation in a German field near Harilaid on July 15, 1919. Six marines were killed: boiler operators John Amey, Alexander Birch and Arthur Primmett, carpenter Robert Johnson and engineers James Gillies and Thomas Packman