A Post from 2012:
Caterina Sforza was an actual historical figure, whose most famous line was featured by Showtime. She displayed her genitals over the battlements to soldiers who demanded her castle in exchange for her kidnapped children. She told them, "You see? I can always make more!" Historic fact: they abandoned the children and fled. She pursued and slaughtered the kidnappers.
This event, however, did not involve the Borgias.
Her scorn and slaughter of her children's kidnappers was only one of many outrageous acts committed by Caterina, who was known as the "virago" (female soldier) of Forli, and a legend in her own time. If you want her full story, you can find it in my historically accurate e-mystery, A Borgia Daughter Dies, available through Amazon http://www.amazon.com/dp/B007WONQV2#_ or Smashwords http://www.smashwords.com/books/view/151617..
Catherine was certainly involved with the Borgias. Cesare Borgia eventually captured the castle at Forli from her, allegedly raped her, and definitely imprisoned her in the Castel Sant' Angelo. She tells this story herself in A Borgia Daughter Dies.
It's a shame, though, that Showtime portrays Caterina being rescued by her cousin Il Moro--something he did not do-- using weapons that didn't exist yet. (The first musket, the arquebus, was more like a mortar, and probably operated from the ground. Though inventors were racing to downsize the cannon—a topic touched on in my books—it hadn't been accomplished yet.) Caterina got no help from anyone. It demeans her to show her rescued by a male relative who never managed to rescue anybody, including himself. (The French beat him twice.)
The "Virago of Forli" stood on her own.