What events served to see the beginning of the Franco-Prussia War?

The reason for the war was diplomatic disagreements over the future heir to the Spanish throne. In addition, there were also a number of political reasons that led to the outbreak of the war between France and Prussia. At that time, Prussia was striving, no matter what, to unite their lands, and France wanted to prevent this. Thus began the war, which ended with the complete defeat of the French army and the defeat of France.