fmhilton, 
"Kilroy was here" was found on an ancient castle walls.
From about Napoleon's time.
Some things never change and bored soldiers with knives is one of them. Graffiti is their hobby when not fighting..
https://www.cnn.com/2024/05/17/travel/graffiti-english-castle-napoleon-scli-intl-scn/index.html