In 1917, the king was very busy making proclamations about the Royal Family going forward. The war with Germany had focused his mind to the extent that he not only stripped his German relatives of their titles and rights in the UK, he narrowed down who could use HRH and be entitled to use Prince or Princess and finally, and most poignant, he relinquished the use of German titles by the family and changed their name from Saxe-Coburg and Gotha to Windsor.

By the KING.

A PROCLAMATION declaring that the Name of Windsor is to be borne by his Royal House and Family and Relinquishing the Use of All German Titles and Dignities.

GEORGE R.I.

WHEREAS We, having taken into consideration the Name and Title of Our Royal House and Family, have determined that henceforth Our House and Family shall be styled and known as the House and Family of Windsor:

And whereas We have further determined for Ourselves and for and on behalf of Our descendants and all other the descendants of Our Grandmother Queen Victoria of blessed and glorious memory to relinquish and discontinue the use of all German Titles and Dignities:

And whereas We have declared these Our determinations in Our Privy Council:

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:

And do hereby further declare and announce that We for Ourselves and for and on behalf of Our descendants and all other the descendants of Our said Grandmother Queen Victoria who are subjects of these Realms, relinquish and enjoin the discontinuance of the use of the Degrees, Styles, Dignities, Titles and Honours of Dukes and Duchesses of Saxony and Princes and Princesses of Saxe-Coburg and Gotha, and all other German Degrees, Styles, Dignities. Titles, Honours and Appellations to Us or to them heretofore belonging or appertaining.

Given at Our Court at Buckingham Palace, this Seventeenth day of July, in the year of our Lord One thousand nine hundred and seventeen, and in the Eighth year of Our Reign.
GOD save the KING.

(London Gazette, issue 30186, July 17, 1917, p. 1.)