The series was born from an initial project titled "Ambulance 14", developed by screenwriter Cécile Lorne as part of the CNC innovation support fund and centered on the story of three women, before producer Iris Bucher accompanied her in the rewriting and proposed it to TF1.

A fourth female lead, a factory manager, was added to the original script once TF1's approval was obtained, and her character became so developed during writing that it ended up having the same importance as the other three.

The idea of reuniting Audrey Fleurot, Camille Lou and Julie de Bona, the actresses from Le Bazar de la Charité, in new roles was proposed to them while shooting for that first series was not even finished, which surprised them.

Camille Lou agreed to play in Les Combattantes without having read the script or knowing what role she would be given, solely out of trust in the artistic team.

The role of Caroline Dewitt was written with Sofia Essaïdi directly in mind, whom the team had noticed in La Promesse, so much so that no casting was necessary for this character.

Young actor Mikaël Mittelstadt, coming from the series Ici tout commence, got the role of soldier Gus without any auditions, a first for him, learning the news through a simple text from his agent.

Filming took place from May 12 to July 13, 2021, mainly in the Vosges (Plombières-les-Bains, Senones, Lac de la Maix, Vexaincourt, Gérardmer), but also in Pas-de-Calais, Somme and Seine-et-Marne, with a team of 150 people, up to 350 people per day on set and 3,000 extras in total.

To recreate the village of Saint-Paulin in Plombières-les-Bains, the production designer had 90 tons of earth brought in to cover the asphalt of the streets and create period shop fronts.

The convent-military hospital of the series was filmed in two different and distant locations within the same scene: the Chartreuse of Neuville-sous-Montreuil and the Abbey of Valloires, where a character can open a door in one place and appear in a room filmed at the other.

Director Alexandre Laurent was in the habit of playing music on set, sometimes even rap as a joke, to motivate the teams and create emotion before takes.

Tom Leeb confided that he needed time to adapt on his first day of filming faced with the very realistic reconstruction of the military hospital, with 150 screaming extras, liters of fake blood and very raw wound effects.

Similar scenes to those in the series actually took place at the Chartreuse of Neuville-sous-Montreuil, which was genuinely transformed into a military hospital during the First World War.

Released internationally on Netflix under the title Women at War from January 19, 2023, the series reached the top 10 in 58 countries, ranking notably number 1 in Brazil, number 2 in Great Britain and number 3 in the United States.

The international success of Le Bazar de la Charité on Netflix, which had generated remakes in Turkey and Italy, prompted TF1 to bet on a new historical epic with the same actresses for Les Combattantes.