Keep accents on capital letters (for French, Spanish and any language containing accented characters)
While writing in a language containing accented characters, accents should be kept, even on capital letters.
Therefore you should write “Belle Époque” instead of “Belle Epoque”, “DÉTENTE” rather than “DETENTE”, etc.
Note
You are strongly encouraged not to write long sections of text in capital letters, because they make reading tiresome.