That started with Bismarck’s wars of unification in the 1860s. Earlier, the French had been the big disruptors and disturbers of Europe’s peace, but Frederick the Great’s armies had been quite effective. Prussia punched above its weight class.
Speaking of disrupters, I was taught in high school history that Britain's foreign policy, for many centuries, was to prevent the European continent from uniting. Britain always meddled to thwart whichever nation was rising in power, switching sides as needed.
It gave rise to the term perfidious Albion.