William, however, hesitated to accept the constitutional title, as he feared that it would overshadow his own title as King of Prussia. He also wanted it to be "Kaiser von Deutschland" ("Emperor of Germany"), but Bismarck warned him that the South German princes and the Emperor of Austria might protest. William eventually—though grudgingly—relented and on 18 January, in the Hall of Mirrors in the Palace of Versailles, he was proclaimed "Kaiser Wilhelm". The date was chosen as the coronation date of the first Prussian king in 1701. In the national memory, 18 January became the day of the foundation of the Empire ("Reichsgründungstag"), although it did not have a constitutional significance.