How did Marx's ideas come to directly impact society?How did Marx's ideas come to directly impact society?
Marx's ideas came to impact society most directly after the Bolshevik Revolution of 1917 in Russia.
Karl Marx had written his books around 50 or 60 years before the Bolshevik Revolution. Of course, the books had impacted some people, making them think about how to reform their societies. However, no society actually came to be run (or at least to say it was run) on Marxist principles until the Soviet Union was created after the Bolshevik Revolution.
After the USSR came into being, Marxist ideas came to impact many other societies. The countries of Eastern Europe became communist. So did China, North Korea, and eventually Vietnam. These societies were, therefore, directly impacted by Marx's ideas.
So you can accurately say that Marx's ideas came to directly impact society through the Bolshevik Revolution, the creation of the Soviet Union, and the post-WWII spread of communism.
Still I wonder at the ad to the right for Welch's juice. Joseph Welch was one of the founders of the ultra-right wing John Birch Society which was vehemently anti communist. Although my father received a silver star with oak leaves and two bronze stars, landed on D-Day and was finally mustered out of WWII with a 40% disability, at the urging of the John Birch Society, he was called before the House Un-American Activities Committee to explain himself. Yes, misused, the word communism became hated. But hate was not limited to communists. It is much like the first words of Rousseau's Emile: “Everything is good as it leaves the hands of the Author of things; everything degenerates in the hands of man.”
As for China and those pesky falling domino countries, each has perverted Marx and Engels' definition of communism in the same way Stalin did. Even Hitler called his party the National Socialists. With the exception of these few rogue nations, mixed economies are exactly what developed. Look at any Nordic country, almost all European countries, The UK and its Commonwealths, or the USA, and it is clear that Marx was dead on when he stated that the only workable economy was a mixed economy.
Nor was bloodshed limited to communist countries. The brutal suppression of the Progressives and, later, the McCarthy anti-communist hearings in the US, the crushing of the Welsh miners in the UK, the horror that was South Africa were all, in large part, fuelled by various government's needs to oppose and interference with unionism or communism. Even the Swedish-speaking minority that held Finland under its thumb attempted to erase the Finns history: Finnish last names were outlawed, the Swedes micro-managed the Finns' economy, and, in general, treated Finland like any other colony. It was the Russians, not the Allies, who liberated Finland.
Unfortunately, because some very bad leaders terrorized their countries under the banner of communism, just as others terrorized people in the name of fascism, what Marx wrote became lost in the violence.
I think you might have conflated two ideas here. Marx was an economist and not a political thinker on the level we associate with the philosophes. Marx did hold that the move to socialism would entail, at the least, political upheaval which he named communism. However, as Marx clearly states in "The 18th Braumire of Louis Napoleon," this period of what most in the USA call communism, but which Marx carefully called the dictatorship of the proletarian, would last no longer than a century and then give way to democracy. In the case of the USSR, Marx overestimated how long the process would take. Note, I am not saying the bits and pieces of the former USSR are shining examples of democracy, they aren't. I tend to think of them as Richard J. Daley's Chicago machine politics writ large.
When the "Communist Manifesto" was published in 1848, Marx did challenge who owned the fruits of an individual's labor. In doing so, he was echoing what was to become a truism: the clash between an industrialized north and an agricultural south which was played out across Europe and the USA. However, Marx never called for the permanent imposition of communism. Rather he spoke of the need for societies to re-invent themselves and to ultimately emerge as democracies with a mixed socialist/capitalist economy,