The grand-duke had from the first been opposed to the war with Prussia, but had been forced to yield owing to popular resentment at the policy of Prussia in the Schleswig-Holstein question.
Found that the Schleswig-Holstein question might be reopened to the detriment of his Hanoverian possessions.
In the former, in spite of, or perhaps because of, the attempt to crush the Polish language and spirit, the Polish element continuously increased, reinforced by immigrants from across the frontier; in the latter the Danish language more than held its own, for similar reasons, but the treaty signed on the 11111 of January 1907 between Prussia and Denmark, as to the status of the Danish optantsin the duchies, removed the worst grievance from which the province was suffering (see SCHLESWIG-HOLSTEIN QUESTION).
During the next two years he continued to support the cause of the duchies, and in 1850, with Carl Samwer, he published a history of the dealings of Denmark with Schleswig-Holstein, Die Herzogthiimer Schleswig-Holstein land das Kiinigreich Ddnemark seit dem Jahre 1806 (Hamburg, 1850).
The opposition of the crown prince to the ministers was increased during the following year, for he was a warm friend of the prince of Augustenburg, whose claims to Schleswig-Holstein Bismarck refused to support.
The issue was forced by the developments of the tangled Schleswig-Holstein Question, which led to the definitive breach between the two great German powers, to the campaign of 1866, and the collapse of Austria on the field of Kiiniggratz (July 3.
Five days later, in spite of this, she sent an ultimatum to Berlin, demanding the continuance of the Prussian disarmament and an immediate settlement of the Schleswig-Holstein question.
Reluctantly he assented to the policy which led to war with the combined power of Austria and Prussia, and to the separation of the duchies of Schleswig, Holstein and Lauenburg from Denmark (see Schleswig-Holstein Question).
The events that followed; the occupation of the duchies by Austria and Prussia, the war of 1864, gallantly fought by the Danes against overwhelming odds, and the astute diplomacy by which Bismarck succeeded in ultimately gaining for Prussia the seaboard so essential for her maritime power, are dealt with elsewhere (see Schleswig-Holstein Question).
Watched as he was by countless enemies at home and abroad, a single false step would have brought ruin and disgrace on himself; the growing national excitement would have burst through all restraint, and again, as fifteen years before, Germany divided and unorganized would have had to capitulate to the orders of foreign powers (see Schleswig-Holstein Question).