H.P. Hansen sat in the German Reichstag as the representative of the Danish-minded community in North Schleswig. In the autumn of 1917, when a German defeat seemed likely, he began paving the way for demanding a plebiscite and reunification with Denmark.

On 22 December 1917 there was a meeting of the executive committees of the major Danish associations. They passed a resolution that a statement be read to the Prussian State Diet setting out their demand for the right to self-determination.

There were some who doubted the possibility of reunification. To them, H. P. Hanssen replied: “The final defeat of Germany is inevitable … I do not doubt that when peace is made we may achieve our goal, if only we keep our wits about us and be ready boldly to intervene when the moment is right”.

In January 1918 US President Woodrow Wilson made public his ’14 Points’ for the coming peace. The right to self-determination was a central element in this document, but North Schleswig was not mentioned as an area where self-determination might apply. So it was still too early for the Danish-minded Southern Jutlanders, led by H.P. Hanssen, to move into action.

Two major German offences in the spring of 1918 (March-April and May-June) seemed for a while to be successful, but a third offensive in July-August failed, and a major allied counter offensive was launched.

The allies broke through on 8 August – ‘The black day of the German army’. On 13 August, the German generals, Hindenburg and Ludendorff advised their government to seek an armistice.

H. P. Hanssen now knew that the German collapse was imminent. He made an agreement with representatives of the Polish minority in the Reichstag that they together would put forward their demand for the right to self-determination.

On 9 October 1918, H. P. Hanssen reached an agreement with the two Southern Jutland members of the Prussian State Diet to the effect that they would work for a border south of Tønder and north of  Flensburg. Their proposal was accepted at a meeting in Flensburg on 12 October.

Then, on 23 October 1918 in the German Reichstag, H. P. Hanssen stated his demand for the reunification of North Schleswig with Denmark. The armistice came into force on 11 November, bringing the World War to an end.

The claim for the right to self-determination could now be made. The final formulation of this claim on the part of the Danish Southern Jutlanders took place at a meeting of Electors Association at the ‘Folkehjem’ in Aabenraa on 16-17 November 1918.

At the close of the meeting, H. P. Hanssen spoke from the balcony of the Folkehjem to the assembled crowd of 3,000 people, assuring them that the likelihood of reunification with Denmark was very strong indeed.