Consider Her Ways by Frederick Philip Grove

We did not remain in as continuous a contact with this new ant of the genus Polyergus (the species varied with the locality) as we had been, let me say, with the Ecitons of the isthmus or the Pogonomyrmex of the slopes; we met them only occasionally; but when we did, we had to admit that, as far as sheer courage and military brilliance were concerned, Pogonomyrmex and Ecitons had been mere amateurs and bunglers. Both Ecitons and Pogonomyrmex had been formidable chiefly through their numbers; but the colonies of Polyergus were not populous. Neither was their sting as formidable as that of Pogonomyrmex; nor their jaws as large as those of Eciton. They were perhaps the most beautiful terrestrial creatures whom it was our fate to meet with in the whole course of our expedition. They were wine-coloured; or, when two-coloured, the gaster was black and the rest of the body a delicate mauve-red; or, towards the Atlantic seaboard, the reverse. As for their stature, the first species we met, which Bissa-tee called Polyergus Breviceps, were stockily-built, and their legs were short; but as we advanced and met with the two-coloured species, their stature underwent a corresponding change, becoming slenderer, longer- legged, and more elegant, till, in Polyergus Lucidus, the largest of them all, we had to acknowledge that, owing to the delicate proportions of their slim and shining bodies, their long, gracefully articulated legs, and their brilliant colouring, we seemed to see the ideal of earthly beauty. Strange to say, among these, the male was the greatest marvel, for the colour-scheme of the body was almost miraculously enhanced by the fact that their wings were pure white.

But what made them such formidable enemies? Their morale.