Britain’s King George V changes royal surname

On June 19, 1917, the British Royal Family, which has had strong German ties since George I, renounced its German names and titles and adopts the name of Windsor. From the article:

"Britain’s King George V changes royal surname
On June 19, 1917, during the third year of World War I, Britain’s King George V orders the British royal family to dispense with the use of German titles and surnames, changing the surname of his own family, the decidedly Germanic Saxe-Coburg-Gotha, to Windsor.

The second son of Prince Edward of Wales (later King Edward VII) and Alexandra of Denmark, and the grandson of Queen Victoria, George was born in 1865 and embarked on a naval career before becoming heir to the throne in 1892 when his older brother, Edward, died of pneumonia. The following year, George married the German princess Mary of Teck (his cousin, a granddaughter of King George III), who had previously been intended for Edward. The couple had six children, including the future Edward VIII and George VI (who took the throne in 1936 after his brother abdicated to marry the American divorcee Wallis Simpson). As the new Duke of York, George was made to abandon his career in the navy; he became a member of the House of Lords and received a political education. When his father died in 1910, George ascended to the British throne as King George V.

With the outbreak of World War I in the summer of 1914, strong anti-German feeling within Britain caused sensitivity among the royal family about its German roots. Kaiser Wilhelm II of Germany, also a grandson of Queen Victoria, was the king’s cousin; the queen herself was German. As a result, on June 19, 1917, the king decreed that the royal surname was thereby changed from Saxe-Coburg-Gotha to Windsor.

In order to demonstrate further solidarity with the British war effort, George made several visits to survey the troops at the Western Front. During one visit to France in 1915, he fell off a horse and broke his pelvis, an injury that plagued him for the rest of his life. Also in 1917, he made the controversial decision to deny asylum in Britain to another of his cousins, Czar Nicholas II of Russia, and his family, after the czar abdicated during the Russian Revolution. Czar Nicholas, his wife Alexandra and their children were subsequently arrested and later murdered by the Bolsheviks."