William I (1797-1888) was king of Prussia from 1861 to 1888 and emperor of Germany from 1871 to 1888. He was the first of the three Hohenzollern rulers of the German Empire of 1871-1918.

Born in Berlin on March 22, 1797, William I was the second son of Prussian king Frederick William III and Queen Luise. William spent much of the Napoleonic Wars as a somewhat sickly refugee in Konigsberg, Memel, and St. Petersburg. He participated in the 1813-1814 War of Liberation, gaining an Iron Cross for action at Bar-sur-Aube and being promoted to general major on his twenty-first birthday.

After a brief "forbidden romance" with Princess Elizabeth Radziwill, in 1829 William wed the lively Princess Augusta of Saxe-Weimar, with whom he enjoyed a happy marriage despite habitual arguments. William became heir presumptive in 1840 on the accession of his childless brother, Frederick William IV. This fact, and his military conservatism, made William the "Cartridge Prince...