"The Islamic State has always been adamant that women should participate in violence only under circumstances of 'defensive jihad', or in simpler terms, only when Muslim lands are under attack and it is strategically necessary," said Devorah Margolin, a senior research analyst at the War Studies Department of Kings’ College London.

Like many other violent Islamist groups, Isil had wanted women to be wives, mothers and the educators of the next generation of believers.

“The loss of physical territory for them really seems to have been the final straw,” Ms Margolin told the Telegraph.

“With their shift in rhetoric around the summer of 2017 (the final days of the offensive in the Iraqi city of Mosul), we have not seen women fighting in the way we would have expected. However, with the last stand in Baghuz, we are seeing that act of defensive jihad really put to the test, and we are seeing women take up arms.”

She said for a group like Isil the use of women in combat gives a sense of its desperation, used not only because they need the "manpower", but also to shame men into action.

Pictures circulating on social media of the bodies of women inside Baghuz have stirred anger among Syrians, who say the US-coalition and its local allies have not taken sufficient care to protect civilians.