The Treaty of Westphalia is a landmark in the history of Europe. It marks a dividing line between the two epochs viz. the era of religious wars and the era of political aggrandizement. The religious antagonism which constituted the basis of rivalries during the earlier period was replaced by dynastic rivalries for the acquisition of territories and evolution of empire.
Secondly, it laid the foundations of the political system of Europe. The territorial readjustments and geographical arrangements made by the Treaty of Westphalia continued to be the basis of the state system in Europe till the French Revolution of 1789.
The arrangements made at Westphalia also exercised a profound influence on the future course of Europe's history, because the changes it registered in the relative positions of the Powers contained the germs of future competition. Thus the future rivalry between Germany and France, largely the outcome of the decline of the empire, and stupendous rise of France as well as their rivalry over Rhine.
Likewise the increase in the power of Brandunburg led to the rise of the modern Prussian state which ultimately wrested hegemony of Germany from Austria. Thereafter the Hapsburgs of Austria tried to make good their losses on the Rhine by seeking compensation on the Danube.
This led to rivalry between Austria and Russia over the control of Danube and territory of the Turks in the East. In short, we can say that the future history of Europe was greatly influenced by the settlement of Westphalia.
Thirdly, the treaty provided an impetus to the development of International Law. The Thirty Years' War not only demolished the pretentions of the emperor to temporal headship of Europe but also the spiritual supremacy of the Pope. As a result the state system of Europe came to be based on the principle of equality of status and complete independence of the states.
Henceforth Pope ceased to play the role of international mediator and the diplomats and ambassadors came to play a more active role in this regard. The peace contributed to the development of international law in another way. The horrors, atrocities and savagery of the Thirty Years War obliged the leaders to think of evolving a code of internationl laws for the regulation of warfare.
It was felt that certain rules must be formulated fc the protection of the non-combatants during the war. Several treatise on International Law were produced, the most notable one being Grotius's On the Law of War and Peace. Above all, the treaty itself set the precedence of holding diplomatic congresses to settle the problem of war and peace through negotiations.