Wilhelm I (William I; William Frederick Louis; German: Wilhelm Friedrich Ludwig; 22 March 1797 – 9 March 1888) was King of Prussia from 1861 and German Emperor from 1871 until his death in 1888. A member of the House of Hohenzollern, he was the first head of state of a united Germany. He was regent of Prussia from 1858 to 1861 for his elder brother, King Frederick William IV. During the reign of his grandson Wilhelm II, he was known as Emperor Wilhelm the Great (German: Kaiser Wilhelm der Große).
The second son of Prince Frederick William and Louise of Mecklenburg-Strelitz, Wilhelm was not expected to ascend to the throne. His grandfather, King Frederick William II died the year he was born, and his father was crowned Frederick William III. Wilhelm fought with distinction during the War of the Sixth Coalition, and afterwards became a prominent figure within the Prussian Army. In 1840, his childless elder brother became King of Prussia, making him heir presumptive. Wilhelm played a major role in crushing the Revolutions of 1848 in Germany, although he was briefly forced into exile in England. Frederick William IV suffered a stroke in 1857 and was left incapacitated, and Wilhelm was formally named Prince Regent a year later. In 1861, Wilhelm ascended to the Prussian throne on his elder brother's death.
