I was reading through the music for Clair de Lune by Claude Debussy a few days ago and I realized that I am often surprised when I see expressive markings (dynamics, tempo, accents and the like) that are not in the standard Italian. How did Italian become the standard for expressive markings in the majority of notated music?
I do know that a great deal of music (especially from the Romantic period forward) has these markings in whatever language is appropriate to the composer or to the piece; however, most music uses dynamic markings like Forte and Piano regardless of the primary language of the composer or the language in which the piece is written.