"Recently invented" trebuchet used in 1304, "a weapon first documented in the 12th century". Something's amiss.

Trebuchets were certainly used by Richard the Lionheart and Phillip II - God's Own Sling and Bad Neighbour (Malvoisin) respectively.

I'm pretty sure Frederick Barbarossa used a custom-made Shelby Cobra outfitted with rapid-firing machine guns. He might have had a hard time turning it on though.