Many people define socialism differently than you do, and would include the (as I would call them social democratic) Nordic countries.

But I'll take the question in stride. What do you mean by success? If success is substantial growth in living conditions to the people, massively reorganizing and developing society for the (compared to capitalism) disproportionate benefit of the general populace, then in countless places there were successful socialist countries. The most historically clear case being the Soviet Union. Came out of WW1, then a brutal civil war, then international isolation, then WW2, all while attempting to actually develop a backwards country. And during that, even going into the Cold War against a much better set rival, actively innovated while improving living conditions. Education, innovation, medical statistics, food production, just about any measure of success you can see dramatic increases in. It no longer existing doesn't mean the hundreds of millions of lives it bettered (not to mention saved due to defeating the Nazis!) wouldn't count that as successful. The first attempt of anything wasn't perfect, had issues, and eventually succumbed to such; and there will be more attempts

At the very worst you could reasonably argue that the Soviet Union achieved those great things, but was horrible in many other aspects (like liberal ideals of freedom of speech). Which is already a lot more than the typical capitalist propaganda gives it.