Creation of the House of Windsor
Due to Albert, Prince Consort, spouse of Queen Victoria, the Royal Family was styled Saxe-Coburg Gotha. But during the First World War growing resentment against Germany caused strain on the Royal Family due to their German ancestry stretching back to the Hanoverian monarchs.
As the war progressed many were beginning to think of the Royal Family as German and all their allegiance was to Germany and not to the British War Effort. When a G.VI Gotha Bomber directly attacked London, more burden was placed on the increasingly worried George V. The belief was that monarchies were going to die out and with the Russian Monarchy on the verge of abolition, George V decided that all members of the British Royal Family were to renounce all German titles and create a new Royal House and Family name which was predominately British.
So the search began and it was at Windsor Castle where a meeting was held and one attendee suggested Windsor, the place they were and it was decided Windsor would be the Family name and Royal House.
So in the London Gazette on the 17th July 1917 it was announced that all German titles were to be renounced and the Royal House and Family were to be styled Windsor.
"Now, therefore, We, out of Our Royal Will and Authority, do hereby declare and announce that as from the date of this Our Royal Proclamation Our House and Family shall be styled and known as the House and Family of Windsor, and that all the descendants in the male line of Our said Grandmother Queen Victoria who are subjects of these Realms, other than female descendants who may marry or may have married, shall bear the said Name of Windsor..." (London Gazette, 17th July 1917).
It is believed Windsor Castle is the inspiration for the family name due to the Round Tower being the family's insignia and the family's ties with the town of Windsor, Berkshire, the ancestral home of the Monarch.
Many members didn't participate in the name change and were removed from the British Royal Family and had all British titles removed and were exiled from British society. Members who did relinquish their titles were the Tecks (Queen Mary's family) and the Battenbergs (Anglicized-Mountbatten) who lost their German titles but were compensated with British Peerages such as the Marquessate of Cambridge, Earldom of Eltham, Viscounty Northallerton, Earldom of Athlone (Tecks) and Marquessate of Milford Haven, Earldom of Medina and Viscounty Alderney (Mountbatten's).