As a historical fiction author writing books, I’m continually amazed at the many—often unsung—ways women contributed to the war effort in Britain during World War II. The Lightseekers is an ongoing series of articles that highlights some of their work and the ways they brought light to Britain in one of its darkest times.

When the National Service Act was passed in December 1941, all unmarried British women and childless widows between the ages of 20 and 30 found themselves staring down the possibility of being called up. However, since the start of the war, thousands of women had already joined the three major military auxiliary services meant to support the army, navy, and air force.

The Navy’s auxiliary branch was called the Women’s Royal Naval Service (WRNS). At one point during the war, posters shouted “Join the Wrens—free a man for the fleet,” encouraging women to choose the popular—and poshest—auxiliary. Even the Wrens smart blue uniform was considered enviable.

“The Wrens officer’s uniform was a lovely dark navy and it was the most coveted uniform by a mile,” Laura Clouting, curator of the Imperial War Museum exhibition on Fashion on the Ration, told the Telegraph in 2015. “A lot of women wanted to join the Wrens purely to get that uniform. The ATS uniform was not quite so loved, despite Princess Elizabeth being its most famous member.”

Wrens were expected to take on roles that would allow men to deploy to much-needed combat roles at sea. This meant that after completing her training, a Wren could be asked to serve as a clerk, cook, mechanic, driver, or weather system and radar operator. Some women were even trained to fly and transport planes from factories to bases for the Navy’s Fleet Air Arm.

The Wrens served both at home and overseas. Australia, Canada, India, and New Zealand all had different versions of the Royal Naval Services.

As conscription grew to include women up to 43 years of age, the number of Wrens in services swelled. It was at its largest with more than 74,000 women working in the auxiliary in 1944.

Like their sisters in other auxiliaries, the Wrens weren’t immune to the dangers of war despite not holding combat roles. 303 members of the service lost their lives during World War II.

If you would like to read more about the extraordinary work that the Wrens did during World War II, the BBC’s WW2 People’s War archive has a dedicated page with transcripts of oral histories that you can access.

Read every story of the The Lightseekers in the series archive. You can also read more extraordinary stories about women in World War II in The Light Over London and my upcoming book The Whispers of War.