This article offers the best, most accurate, most concise history of class conflict under capitalism in the 20th century that I have ever seen. Not that it's perfect because it leaves a lot of important details out such as Operation Gladio under the direction of the CIA which used terrorist methods against militant workers in Europe following WWII to insure that only capitalist parties would triumph.
The fact that this sort of accurate history is so unusual is simply due to the triumph of capitalist classes, especially the dominant capitalist class in the US, following WWII. The emerging US capitalist class has tried, and largely succeeded, in re-writing the history of this post-WWII era and re-defining important political-economic concepts (socialism
It is clear to me and this history that social democracy has always been a temporary strategy by ruling capitalist classes to stave off working class interests in public ownership and control of economies.
...World War II was an economic boom for the USA [mostly for the capitalists]. Its weapons, oil, steel, auto, and construction industries grew manifold. Their surplus financed the Marshall Plan to rebuild the capitalist economies of Western Europe and prevent socialist-communist electoral victories. This policy succeeded, especially in Greece and Italy where a majority of workers were leftist.
Europe’s two largest political parties, the Social Democrats and the Christian Democrats, adopted and even extended welfare benefits enabled by the Marshall Plan. The “free market” has since largely replaced the state as the politically determining force, and the welfare model is no longer viewed as necessary.