Verb
(military) To march or charge out of the designated order in a military unit.
(idiomatic) To publicly disagree with one's own group or organization.
Source: en.wiktionary.orgI knew that until I was ready to tell the truth as I saw it, I was no better than a politician- but I didn't know whether I would ever be brave enough to break ranks and speak my mind. Clarence Thomas
The kings made us drunk with fumes, Peace among us, war to the tyrants! Let the armies go on strike, Stocks in the air, and break ranks. If they insist, these cannibals On making heroes of us, They will know soon that our bullets Are for our own generals. Eugène Edine Pottier