We might also consider ISIS in the vein of our own late Confederate South.
I think this is a really revealing analogy. The Confederacy was founded on white supremacy (as announced clearly at the secession conventions, by Davis, Stephens, etc.) and adamantly opposed to arming Blacks. In fact, Gen. Forrest massacred all the surrendering Black soldiers at Ft. Pillow in order to send a message about how wrong he thought it was for Blacks to be fighting in what he considered a white man's war. But the Union Army was nearly 10% Black, and in some campaigns the proportion of Black troops was much higher. Not only did this increase the North's manpower advantage, but it also provided a great stimulus for Black slaves to run away and seek refuge behind Union lines, or to join the Union army themselves. In March 1865, when the Confederate situation was desperate, the Confederate government finally authorized enlistment of Blacks in exchange for their freedom; but only about 50 Blacks were mustered by the time Lee surrendered about a month later (compared with nearly 200,000 in the Union Army).
Fast forward to 2014. The Kurdish People's Protection Units who are leading the fight against ISIS in Syria are 40% female, and the presence of women on the battlefield was arguably crucial to reversing ISIS's offensive and retaking important captured territory. ISIS is committed to a reactionary sexist ideology, so we can only assume that if it is asking women to fight its battles, that strategy is born of desperation. We can only hope that ISIS's straits today are as dire as the Confederacy's in March 1865.
