The primary similarity of the wars mentioned that all were the result of efforts at territorial expansion; although all had different results. All also involved changing alliances as a result of the concept of balance of power which was important to Europe at the time. Additionally, nationalism, a fairly new concept at the time, first emerged during these wars.
The Seven Weeks War, also known as the Austro-Prussian War, was instituted by Otto von Bismarck to not only gain territory to the north of Prussia but also to unite the people of all of Germany with him to build the concept of German nationalism. A secondary goal was to isolate Austria from the rest of Germany, thereby allowing Prussia to become the dominant power in uniting the German states. Bismarck went to great pains to keep France neutral in the contest; and also offered surprisingly lenient terms to Austria at its end. He had already made plans for a war with France, and did not want Austria to become bitter and isolated. Prussia gained the provinces of Schleswig and Holstein as a result of the war. Afterward, Bismarck provoked a war with France. His lenient terms to Austria precluded Austria from entering the war on behalf of France. At the end of the Franco-Prussian War, Bismarck was surprisingly brutal. He not only took the disputed provinces of Alsace-Lorraine as German territory; he had Frederick Wilhelm I crowned Kaiser of the German Empire at the palace of Versailles, a painful insult.
The Crimean War was the result of Russian attempts under Czar Alexander II to take Constantinople and the Crimea from the Ottoman Empire. Britain and France, alarmed at the possibility of r Russian expansion, and control of the Black Sea, came into the war on behalf of the Ottomans. Although not often noted in textbooks, the war was especially bloody. it is noteworthy that Britain and France, Christian countries, went to war with Russia, another Christian country, on behalf of the Ottomans, a Muslim Empire. This point illustrates the importance to European nations of the balance of power.