666 Ch. 17 • The Era of National Unification

Prussian coastal battery during the war against Denmark, 1864.

The London Protocol of 1852 placed Schleswig-Holstein under the

authority of the Danish king, but forbade their incorporation into Denmark.

In March 1863, however, the Danish king enacted a new constitution that

seemed to incorporate Schleswig into his kingdom. Bismarck, capitalizing

on the wave of nationalistic support, then found an ally in Austria. Prussia

issued Denmark an ultimatum in January 1864, demanding that the new

constitution for Schleswig be redrawn. The Danish government, incorrectly

assuming that because of Schleswig’s strategic importance, France and

Britain would rush to its defense, rejected the ultimatum and found itself at

war with Prussia and Austria. To no one’s surprise, the Danes were easily

beaten. The Treaty of Vienna (October 1864) established the joint adminis­

tration of Schleswig-Holstein by Prussia and Austria—Austria would

administer Holstein, and Prussia would administer Schleswig. This awk­

ward arrangement left Prussia with a military corridor and communica­

tions line through Austrian-controlled Holstein and use of the port of Kiel.

Bismarck now viewed a military showdown with Austria as inevitable,

even desirable. Yet, while preparing for that eventuality by currying the

favor of the smaller German states and working to isolate Austria further

from the other European powers, he blithely tried—and failed—to tempt

Austria into making an agreement that would formally divide their influ­

ence in the German states into north-south spheres. Bismarck persuaded

Napoleon III that France would receive territorial compensation in the

Rhineland if it would stay out of an Austro-Prussian war. The French

emperor tried to play both sides. Convinced that Austria could defeat Prus­

sia, he signed a secret treaty with the Habsburg monarchy that would give

the French Venetia and establish a French protectorate in the Rhineland

after an Austrian victory.

Bismarck then drew Italy into a secret alliance, signed in April 1866, by

promising it Venetia in the event of a Habsburg defeat. Italy promised Prus­

sia assistance if there was war with Austria, knowing that a Prussian vic­

tory would add the last large chunk of the Italian peninsula to Italy (see

P- 657).