this is incredibly niche but i'm reading an isekai set around the Second Schleswig War and I am completely thrown because they're drinking coffee out of mugs, the modern mug is an invention of WWII.

people before drank coffee in wide brimmed or demitasse half-cups.

If you drank Turkish concentrated coffee, you drank it out of a demitasse cup

if you drank a weaker brew with milk and sugar, you drank it out of a wide brim cup so you could enjoy the aroma with a pot sitting in hot water to keep it hot

Mugs were to keep it warm for soldiers

@poppyhaze huh! This perhaps explains why my grandmother (born 1923) thought mugs were unacceptable and always used a cup and saucer.
@poppyhaze This is the sort of detail that I'm terrified of getting wrong when trying to write historical fiction.
@benfulton well if you have any weird questions, i'd be happy to answer them, or you can always make up a history for them on the fly.