Final answer:
The Treaty of Frankfurt is seen as a failure in achieving Bismarck's foreign policy aims because it annexed territories from France, creating lasting enmity and failing to promote long-term stability in Europe, contributing to the conditions leading to World War I.
Step-by-step explanation:
The Treaty of Frankfurt is generally seen as a diplomatic failure in terms of Otto von Bismarck's key foreign aims because of the long-term consequences that arose from its terms. The Treaty, which ended the Franco-Prussian War in 1871, led to the annexation of the German-speaking territories of Alsace and Lorraine from France. This annexation created lasting enmity between Germany and France, which contradicted Bismarck's broader aim of maintaining peace and stability in Europe through a balance of power. Additionally, the treaty failed to account for the rise of nationalism and the potential for future conflict, as it imposed harsh penalties on France, which ultimately fueled desires for revenge and contributed to the conditions leading to World War I.
Bismarck's Realpolitik approach manifested in the Treaty of Frankfurt by securing strategic territories without extending hostilities or prompting widespread international backlash in the immediate term. However, the Treaty did not foster the long-term stability Bismarck desired, as it planted the seeds of hatred and desire for retribution in France, which were factors in the eruption of World War I.