What were the reasons for the conflict between the Netherlands and Spain?

The cause of the conflict was the oppression of the people by Spain, as well as the desire of the Netherlands to gain their independence. Thus began the war of liberation, which lasted several decades. It ended with the end of the Thirty Years’ War in Europe. A peace treaty was signed, which correlated with the Westphalian Agreement. So the Netherlands were able to gain their independence, and they were also able to get the territories captured during the war.