Flower-class sloop

The Flower class comprised five sub-classes of sloops built under the Emergency War Programme for the Royal Navy during World War I, all of which were named after various flowers. They were popularly known as the "herbaceous borders".

The "Flowers" were designed to be built at merchant shipyards, to ease the pressure on yards specializing in warships. The initial three groups were the first purpose-built Fleet mine-sweepers, built with triple hulls at the bow to give extra protection against loss from mine damage when working. When submarine attacks on British merchant ships became a serious menace after 1916, the existing Flower-class minesweepers were transferred to convoy escort duty, and fitted with depth charges as well as 4.7-inch naval guns.

The latter two groups, the Aubretias and Anchusas, were designed as submarine decoys, or Q-ships, with hidden guns and a distinctive "merchant marine" appearance. These "Warship-Qs" were thus the first purpose-built anti-submarine fighting ships, and their successor types were the anti-submarine sloops of the second world war, which evolved into the modern ASW Frigate during the 1939-45 Battle of the Atlantic.

The five sub-classes were:

Fleet minesweepers: Submarine decoys ("Warship-Qs"):
 * Acacia-class sloop: first group to be built, in 1915. 24 vessels built in two batches of 12. Two sunk during the war.
 * Azalea-class sloop: 12 vessels built in 1915. Slightly modified Acacia's; two sunk during the war.
 * Arabis-class sloop: 36 vessels built 1915, a further eight for French Navy. Five British, and one French vessel sunk.
 * Aubretia-class sloop: 12 vessels built 1916; two sunk.
 * Anchusa-class sloop: 28 vessels built 1917. Saw service as Q ships; six sunk.

Some 112 "Flowers" in total were built for the Royal Navy, and a further eight for the French Marine Militaire. Of these, 17 RN and one French "Flowers" were sunk.

Some members of the class served as Empire patrol vessels throughout the world during the peacetime years between the wars, but almost all were disposed of by the Second world war. This allowed the majority of the class names to be revived in WW2 for the new, smaller Flower-class corvettes.

Two members of the final Anchusa group, HMS Chrysanthemum (1917) and HMS Saxifrage (renamed HMS President (1918) in 1922), survived to be moored on the River Thames for use as Drill Ships by the RNVR until 1988, a total of seventy years in RN service. HMS President (1918) was sold and preserved, and is now one of the last three surviving warships of the Royal Navy built during the First World War, (along with the 1914 Light cruiser HMS Caroline (1914) in Belfast, and the 1915 Monitor HMS M33 in Portsmouth dockyard).