From Indian Summer: The Secret History of the End of an Emperor, by Alex von Tunzelmann (Picador, 2008), pp. 43-45:
ON 28 JUNE 1914, AN AUSTRIAN ARCHDUKE AND HIS WIFE were shot in Sarajevo by a nineteen-year-old terrorist. Assassinations were not unusual at the time. Victims in recent years had included the presidents of Mexico, France and the United States, the empresses of Korea and Austria, a Persian shah and the kings of Italy, Greece and Serbia. Portugal had two kings assassinated on the same day in 1908. But the murder of Archduke Franz Ferdinand would swiftly assume its legendary status as the trigger for the Great War. Swift to feel its tremors was the fourteen-year-old great-grandson of Queen Victoria, His Serene Highness Prince Louis of Battenberg….
Four months to the day after Franz Ferdinand’s death, the elder Prince Louis of Battenberg was removed from his position as First Sea Lord. Prince Louis had been British since 1868 and had served in the Royal Navy since he was fourteen years old. But by October 1914 Britain was at war with Germany, and there were far too many Germans visible in high places. For King George V, of the house of Saxe-Coburg-Gotha, the public tide of anti-German feeling was alarming. He was largely German; his wife, the former Princess May of Teck, was wholly German; his recently deceased father, King Edward VII, had even spoken English with a strong German accent. It was uncomfortably obvious where all this might lead, and a high-profile sacrifice was required to satisfy the public. Prince Louis was at the top of the list.
And so the king and his First Lord of the Admiralty, Winston Churchill, agreed to throw one of their most senior military experts onto the pyre at the beginning of the war, because his name was foreign….
But the humiliation of the Battenbergs was not complete. On 17 July 1917, a mass rebranding of royalty was ordered by George V. The king led by example this time, dropping Saxe-Coburg-Gotha (which was, in any case, a title — nobody knew what his surname was, though they suspected without enthusiasm that it might be Wettin or Wipper), and adopting the British-sounding Windsor. Much against their will, the rest of the in-laws were de-Germanized. Prince Alexander of Battenberg became the Marquess of Carisbrooke; Prince Alexander of Teck became the Earl of Athlone; Adolphus, Duke of Teck, became the Marquess of Cambridge. The unfortunate princesses of Schleswig-Holstein were demoted, in the king’s words, to “Helena Victoria and Marie Louise of Nothing.” And the unemployed Prince Louis of Battenberg would be Louis Mountbatten, Marquess of Milford Haven…. Henceforth, Prince Louis would be a marquess, and Battenberg a cake.