The Women's Royal Naval Service (WRNS), also known as the Wrens, was formed in 1917 during the First World War, as a branch of the Royal Navy.
The initial intention behind the Wrens was that the service would free up men for frontline action by serving in roles such as cooks, dispatch riders and sail-makers.
In 1919, the Wrens were disbanded after the war and the Association of Wrens was founded in 1920 by Dame Katherine Furse, to preserve the unique bonds of friendship formed between women in the Senior Service.
When hostilities broke out in the Second World War in 1939, the Wrens reformed.
One of the slogans used in recruitment posters was "Join the Wrens and free a man for the Fleet".
In 1939, the first Wrens were admitted to the Royal Naval College in Greenwich to undertake officer training, cipher and administration courses.
At its peak, the service had 74,000 officers and ratings, undertaking an expanded number of roles, including wireless telegraphists, electricians, and even flying transport planes.
Wrens were also prominent support staff at the Government Code and Cypher School at Bletchley Park.
Women were not allowed on ships that were going into active service, but Wrens did load torpedoes on to submarines and command and crew powerful harbour launches.
The boat crews also served as coastal mine-spotters, an important and dangerous job.
During wartime, the service lost 303 women.
The Wrens continued in the post-war period until they were amalgamated into the Royal Navy in 1993.
Before then, all women in the Royal Navy were Wrens except nurses, who joined – and still join – Queen Alexandra's Royal Naval Nursing Service, and medical and dental officers, who were commissioned directly into the Royal Navy.
In October 1990, the first female personnel to go to sea joined HMS Brilliant in Devonport.
Three months later, they deployed with the Type 22 frigate to the Middle East, as part of the international naval effort in the First Gulf War.
Female sailors are still often referred to as Wrens or 'Jennies' (Jenny Wrens) in naval slang.
The organisation has just celebrated its centenary at the National Memorial Arboretum, Staffordshire, delayed 12 months after last year's event was postponed due to the coronavirus pandemic.