William I, King (Kingdom of Prussia) : All Data
William I was the King of Prussia from 1861 until his death in 1888. During his reign, he played a crucial role in the unification of Germany. The most significant war that occurred under his rule was the Franco-Prussian War, which took place from 1870 to 1871. This conflict resulted in the defeat of France and the establishment of the German Empire, with William I being proclaimed as its first Emperor. The Franco-Prussian War aligns with the calculated timespan of William I's rule, making it a defining moment of his reign.