I saw a post on r/humansaremetal where two people were sparring in full plate armor with swords and shields and out of the blue one of them throws an MMA style head kick and knocks out the other fighter. Is this an actual historical technique for duels and competitions in Europe? If so, was it common? Follow up question, is this a technique that saw use on the battlefield?
Link to the video: https://www.reddit.com/r/HumansAreMetal/comments/ifm7zs/parry_this_you_filthy_casual/
You might want to try r/wma but the short answer is that push kicks ("sparta kicks") to the stomach/torso and kicks to the low lines (groin, knees) are documented in historical technical sources on personal combat, but not so much kicks to the high line as per that video.