The Weltpolitik (German: world politics) was adopted in Germany fine of the 19th century to replace the preceding approach (namely the Realpolitik ).

The Weltpolitik was a policy more aggressive than the Realpolitik and led to conflicts between Germany and other nations. This policy has a great part of responsibility in the diplomatic crises between great powers which led to the First World War. This policy aimed at finding for Germany a Place with the sun (place in the sun) proportional to its increasing industrial force, and this mainly by developing a colonial empire being able to compete with those of the other great powers. The most important element in this strategy was the construction of the Hochseeflotte: the Fleet of Open sea, a fleet which would compete or even would exceed the Royal Navy the United Kingdom. That led to a naval race germano-British where each one tried to exceed the battleships of the other (see Dreadnought).

In several ways, the Weltpolitik was perceived as being the natural successor of the Nationalisme which influenced a recent part of the history of Germany. The Nationalisme concentrated on the Unification of Germany. When this one was effective, the German nationalists sought to increase the capacity of Germany on the international plan, and for them, to develop a colonial empire was an essential point to reach that point. The doctrines of the social Darwinisme were popular, and launched the idea as the Sélection of most suited the applied as well to the States as to the individuals. If a State did not endeavor to extend, it would weaken or car-be destroyed. All that nourished the Nationalisme which existed already in Germany and led to larger expansionism represented by the weltpolitik.

The United Kingdom obtained friendly agreements with the France and the Russia to avoid the German naval threat, consequently creating a division of Europe in two rival alliances of Great powers: the Triple Alliance of the France, the Russia and of the the United Kingdom; and the Triple Alliance (or Triplice) of the Germany, the Austria-Hungary and the Italy (see First World War). These sets of alliances increased considerably the war risk generalized, a conflict between a member of an alliance with a member of other alliance sufficient to involve the other members in the war by invocation of alliance or presumption that the other camp will call upon its respective alliance. It is what occurred July in August 1914: Germany supported Austriche-Hungary against Russia in Balkans and, considering that any conflict requérerait the German mobilization vis-a-vis in France, applied its Schlieffen plan. The Schlieffen plan implied the violation of the neutrality of Belgium, giving a Casus belli to the United Kingdom via the Traité of London, 1839.