Which country suffered the most loss of territory due to the unification of Italy?

The country that suffered the most loss of territory due to the unification of Italy was the Austrian Empire. This unification process, which culminated in the mid-19th century with the Kingdom of Italy being officially proclaimed in 1861, involved a series of wars and diplomatic maneuvers that significantly impacted the Austrian Empire.

Prior to Italian unification, large regions of northern Italy, including Lombardy and Venetia, were under Austrian control. The Austro-Sardinian War in 1859 and the later involvement in the Austro-Prussian War in 1866 resulted in significant territorial losses for Austria. Lombardy was ceded to France, which then transferred it to Sardinia, while Venetia was lost after the Austro-Prussian War, significantly reducing the Austrian Empire's influence in Italy and changing the political landscape of Europe.

In contrast, the other countries listed either did not have a significant territorial loss due to Italian unification or were not directly impacted by the events of that period. For example, Germany was undergoing its own unification process around the same time, France, while involved in the context of the conflicts, did not suffer territorial losses that were a direct result of Italian unification, and Spain was largely outside