One factor that made war more likely was the unification of Germany and of Italy. The creation of these two new major states altered the balance of power in the European state system; the efforts of statesmen during the next forty years to adjust the system ultimately proved unsuccessful.
The older established powers were unwilling to give up their own claims, and after 1850, with the principle of national sovereignty well established, smaller western European states were no longer open to annexation by the great powers.
