On: The only known trebuchet casualty in history

[agos]

the key word is "known"

[mr_toad → agos]

More like ‘named’. There are accounts of trebuchets causing hundreds of deaths, but individual casualties in medieval battles are rarely identified.

[allturtles → mr_toad]

This person is not named, unless you consider Skeleton 150 a name. 'known' is the appropriate word here.