Milan 1880: What?
In Deaf Education and the Deaf world, Milan 1880 means the Second International Congress on the Education of the Deaf, held in Milan from 6 September to 11 September 1880.

(from: https://www.scielo.br/j/hcsm/a/QkzPkkNgwTzG69wJKDzN66p/?lang=pt&format=pdf)
Another name for the same event: the Milan Conference.
Most people will know that at this Congress, a resolution was accepted that banned the use of sign language in the education of the deaf. It was decided that deaf children had to be educated orally. Teachers and students had to communicate through spoken language. The main objective of the education of deaf children was to teach them to speak and lipread.
But who made this decision? And why? And how is it possible that this resolution - made by a small number of people - had such very far-reaching consequences for centuries to come?

American Annals of the Deaf, 1881