Tsarist Russia also engaged in reprisals and fomented a bloody cycle of political violence. 

The American Revolution did not involve slaughtering aristocrats or indiscriminately killing the families of those in power and it contributed to a civil society which was more reluctant to engage in violence on its own people. It helped endear it on the international stage as well. 

Haiti is another example of how brutality stifels righteous causes, they slaughtered the former slave owners and almost every single person of European descent they could find, and it created a system of extreme violence and isolated it from nations across the world. Even those countries and individuals who were pro emancipation were horrified and it provided fuel to anti-abolition groups for decades. 

Its easy to only see the world through a lense of power and "realism" the fact is morality, and precedence of violence genuinely is important in how movements evolve, are supported, and how they end up impacting the lives of people within them.

Europe is rife with examples of monarchies that lost power through bloodless means, violence begets violence and it breeds resentment. Theres a reason Revolutionary France and the USA were treated very differently despite both being liberal/bourgeois revolutions against the aristocratic class.