Which year is known as the "Year of the Three Emperors" in German history?

The three different emperors who ruled the German Empire in 1888 were Wilhelm I, Frederick III, and Wilhelm II. Wilhelm I died in March 1888 after reigning as emperor and as King of Prussia prior to becoming emperor. A collection of German-speaking states that included the North German Confederation and southern German states, were unified under the rule of Wilhelm during the Franco-Prussian War of 1870-71 to become the German Empire.

Wilhelm I was succeeded by his only son, Frederick III at the age of 56. He served in the army during wars with Denmark, Austria and France, winning the prestigious the "Pour le Mérite" for gallantry. But prior to Frederick becoming emperor, he suffered from problems in his throat (believed to be cancer), including the appearance of a growth. Following surgery and other treatments in 1887, he was left unable to speak and a tube inserted into his trachea to aid his breathing. After succeeding to the throne in March 1888, his condition worsened and he died after only 99 days as emperor.

The new emperor, Wilhelm II succeeded to the throne in June 1888. He had suffered a traumatic breech birth that left him with a withered arm. He would conceal his condition as seen in photos by holding or carrying something in his left hand. His left arm was about 6 inches shorter than his right. Wilhelm reigned until 1918 when he abdicated the throne and spent his last years in exile in the Netherlands. He died in 1941 at the age of 82.