We're not condoning violence, but as you asked about the story, here it is!
Following the death of Libuše, Vlasta led a band of women against the (male) forces of Libuše's widower Přemysl and founded the castle Děvín. The men, however, despite the warnings of Duke Přemysl, just laughed at their preparations. Vlasta then sent the most beautiful girls to enchant the men with their charms, and led an attack against the men who came to Děvín, which the women won.
Šárka, Vlasta's lieutenant, entrapped a band of armed men led by Ctirad by tying herself to a tree and claiming that the rebel maidens had tied her there and put a horn and a jug of mead out of reach to mock her. Ctirad believed her story and untied her from the tree, whereupon she poured mead for the men as a celebratory thank-you gift. Little did the men know that Šárka and the maidens had put a sleeping potion into the mead. When all the men had fallen asleep, Šárka blew the horn as a signal for the rebel maidens to come out of their hiding places and join her in slaughtering the men. Ctirad was captured and then tortured to death in Děvín. The valley where it happened is today called Divoká Šárka (Wild Šárka).