Hi. I've been learning some new words and have a question about "demarche". As for its diplomatic meaning, everything is clear, but I don't know how to use its meaning "a statement or protest addressed by citizens to public authorities". Do you think it's OK to say:

Thousands of Egyptians went on a demarche (a protest demarche)in Cairo.
THANKS.

Your sentence is close. But "demarche" refers to formal petitions, not the more informal demonstrations of the Egyptians.

This site has some sample sentences.

http://www.wordnik.com/words/demarche/examples