During almost any successful revolution, raw, naked force is always the thing that makes the ultimate change, and then keeps the new elite in power. The French Republican Army and the Committee of Public Safety in France, and the Red Army and Cheka in Russia were instrumental in solidifying the hold of the new masters. Neither regime could have taken power or survived without the backing of a huge number of armed men. When Napoleon actually took over the French Republican armed forces, that was the end of the Revolution. Interestingly, socialism in the USSR and their satellites in Eastern Europe was so frickin' bad that even the armed men propping the whole thing up refused to defend it. It just collapsed, and the elites that ran it all were shown the door. Of course a heavily armed populace could be a detriment to any attempt to make them get with a new program, and toe some ideological line. Tell someone with .45 caliber pistol in their hand to shut up. I dare you.