As Emperor Wilhelm's heir, he was the last Crown Prince of the German Empire and the Kingdom of Prussia, until the abolition of the monarchy.

As emperor, Wilhelm's father instructed the crown prince to defer to the advice of his experienced chief of staff Konstantin Schmidt von Knobelsdorf.

[4] In October 1914 Wilhelm gave his first interview to a foreign correspondent and the first statement to the press made by a German noble since the outbreak of war.

[5][6] He denied promoting military solutions to diplomatic problems, and said this in English: Undoubtedly this is the most stupid, senseless and unnecessary war of modern times.

It is a war not wanted by Germany, I can assure you, but it was forced on us, and the fact that we were so effectually prepared to defend ourselves is now being used as an argument to convince the world that we desired conflict.From August 1915 onwards, Wilhelm was given the additional role as commander of the Army Group German Crown Prince.

After the outbreak of the German Revolution in 1918, both Emperor Wilhelm II and the crown prince signed the document of abdication.

On 13 November, the former crown prince fled Germany, crossed into the Netherlands at Oudvroenhoven[8] and was later interned on the island of Wieringen (now part of the mainland), near Den Helder.

In the autumn of 1921, Gustav Stresemann visited Wilhelm, and the former crown prince voiced an interest in returning to Germany, even as a private citizen.

[9]: 11–12 In June 1926, a referendum on expropriating the former ruling Princes of Germany without compensation failed and as a consequence, the financial situation of the Hohenzollern family improved considerably.

Wilhelm joined Der Stahlhelm, which merged in 1931 into the Harzburg Front, a right-wing organisation of those opposed to the democratic republic.

[9]: 13 After the murder of his friend Kurt von Schleicher, the former Chancellor, in the Night of the Long Knives (1934), Wilhelm withdrew from all political activities.

After the ill-fated assassination attempt on 20 July 1944, Hitler nevertheless had Wilhelm placed under supervision by the Gestapo and had his home at Cecilienhof watched.

His wife Cecilie fled in early February 1945 as the Red Army drew closer to Berlin, but they had been living apart for a long time.