Okay. Here is an essay I wrote. It's about the rise of the state but this is essential in the formation of the European state system. The European State system (or diplomacy) recognised states' right over the sovereignty over their own territory and dealt with other sovereign states as equals (meaning they had external autonomy) - so the rise of the sovereign state (which is attributed to Westphalia) is pretty important in this. Anyway, the essay is pretty brief, so if you want to delve deeper into any part of it let me know.

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What explains the rise of the state, and does this have anything to do with the Treaty of Westphalia?

To answer this question, it is necessary to briefly explain two key concepts; firstly, the state and secondly, the Treaty of Westphalia. The state, when used in this essay, is a political unit with clear boundaries that has two key features “internal hierarchy and external autonomy.”1 This means internally there is a clear structure in place for who wields the power and who does not – this is typified by the state having a monopoly on power and violence.2 Externally, they have to be able to act in their own interests without any constraints imposed by a higher authority. In essence, the state is a sovereign political unit; sovereign in the way it rules internally and sovereign in the way it interacts with other political units on the world stage. As for the Treaty of Westphalia, that was a set of two treaties (despite what the name might suggest), the Treaty of Osnabrück (between Sweden and the Holy Roman Empire) and the Treaty of Münster (between France and the Holy Roman Empire), which ended the Thirty Years War.3 Many people, particularly those in the field of international relations, regard Westphalia as the start of the sovereign state and of state system of international politics,4 but this is just a convenient “founding myth”5 for two reasons. Firstly, the Treaty of Westphalia had little to do with sovereignty.6 Secondly, the gradual emergence of the state and the state system was happening long before and long after Westphalia.7
So where does the idea of Westphalia kickstarting the modern state come from? It mostly stems from two ideas; that Westphalia granted states of the Holy Roman Empire (the Empire) the right to form alliances and that the Thirty Years War was an attempt by the Habsburgs to create a “universal monarchy”.8 If Westphalia did indeed grant the Princes of the Holy Roman Empire the right to conduct their own foreign policy for the first time, the theory that the rise of the state was due to Westphalia would hold some water. However, this is simply not true, Westphalia was just confirming a right that German states had been practicing for some time (for example, Brandenburg’s 1605 alliance with the United Provinces of the Netherlands).9 Furthermore, there were two large alliances within the Holy Roman Empire at the outbreak of the war in the form of the Catholic League and the Evangelical Union.10 This is even recognised by the Emperor in 1634 when he put forward a settlement that would allow Princes and cities to have alliances with actors outside the empire but not within.11 So, Westphalia was neither the moment when states in the Empire started conducting their own foreign policy (as this was happening before)12 and it wasn’t when it was first recognised by the Emperor (as that was in 1634).13 Therefore, Westphalia did little to contribute to the rise of the state in this way.
Additionally, it was not a victory of sovereign states against the Habsburg ideas of universal monarchy14 as this was largely propaganda.15 It was propaganda that even the German Princes, who were supposedly (according to the French and Swedish) going to be subjugated by the emperor,16 did not embrace.17 The epitome of the sovereign states victory over the Habsburgs was the independence of the Swiss and the Dutch being secured. But the Swiss did not see themselves as independent after Westphalia18 and the Dutch were already considered independent before Westphalia.19 This demonstrates the Treaty of Westphalia was again just recognising the reality of the situation rather than contributing to the formation of state system.
In fact, Westphalia (in some ways) solidified ideas that went against the state system and the idea of sovereign states. The most obvious example of this would be the fact that Princes could no longer decide religion of their territories (which had been the case since 1555), instead the religious status of the Empire would be frozen.20 This is a clear way in which Westphalia went against the principles of internal sovereignty (which underpin the modern state). Westphalia, also limited alliances that could be made by the states in the Empire (they could not enter an alliance that was harmful to the Empire or one that would breach Westphalia),21 this clearly goes against the principle of “external autonomy.”22 In fact it was the Empire’s courts and the Diet that was meant to uphold Westphalia,23 far from diminishing the role of the Empire this actually codifies it. The Holy Roman Empire continued to exist for over 150 years after Westphalia and was destroyed by Napoleonic France rather than political disintegration,24showing that Westphalia did not contribute (at least significantly) to the rise of the state. Surely if the peace of Westphalia created a system of sovereign states,25 then the Empire would not have been able to survive until the 19th century.
Westphalia, also infringed upon the Sovereignty of actors who were not part of the Empire and relied on these same actors to enforce the treaty.26 The Swedish territorial concessions (that it gained from Westphalia) were still part of the Empire and Swedish rulers had to sit on the imperial Diet to represent them.27 Similarly, the French concession of Alsace was to maintain the autonomy the Austrians had granted it.28 Both of these countries did not have full sovereignty over these territories due to Westphalia and in Sweden’s case their territories had an overlord in the form of the Emperor.29 France and Sweden being guarantors of Westphalia means they could intervene in the Empire’s affairs if necessary.30 All this paints a picture that is contradictory to Westphalia being the impetus for political bodies to have sole authority over their territory.
The rise of the state was not due to Westphalia. It was a process that had been happening gradually for centuries.31 International politics is Darwinian, only the states that are able to defend themselves survive.32 So, war is essential but the process of waging war also created states.33 To wage war an army is needed but an army needs men, provisions and arms – to be able to supply all this, the state will have to develop a means of extracting resources and capital.34 The more efficient the extraction, the more efficient the war making. It was also in a the “sovereign authority’s”35 interest to eliminate internal rivals and to try to centralise power. Once power was centralised enough, it can enact reforms that will improve the economy of the state – standardization, for example.36 Eventually, sovereign state model became the most efficient way to run an economy,37 and thus became the most proficient at war making. In time, more and more states would reform (or attempt to) to the sovereign state model.38 The first state to start this process of centralisation was England after the Norman invasion,39 just under 600 years before Westphalia. It was industrialisation that allowed the state to centralise power to a level never previously seen,40 and it is perhaps this that played the most important role in the rise of the state.
In conclusion, Westphalia did not bring about the rise of the state. It did not recognise states sovereignty over their own territory (most obviously with the Princes no longer being able to choose the religion of their territories)41 and it did not grant “external autonomy”42 (as the states already, mostly, had this).43 Westphalia, by its very nature was against the idea of sovereign states, as it allowed France and Sweden to intervene in the internal affairs of another political entity.44 Instead, the rise of the state is a slow process of centralisation and war making,45 which made the sovereign state the dominant political body as it was the most economically efficient46 and, by extension, the most capable of waging war.

Bibliography
Beaulac, Stephan. “The Westphalian Legal Orthodoxy – Myth or Reality.” Journal of the History of International Law 2000 2
Osiander, Andreas. “Sovereignty, International Relations, and the Westphalian Myth.” International Organization 2001 55 (2)
Spruyt, Hendrick. The Sovereign State and Its competitors. (Princeton: Princeton University Press, 1994)
Tilly, Charles. “War-Making and State Making as Organized Crime.” In Peter B. Evans, Dietrich Rueschmeyer and Theda Skocpol (Eds) Bringing the State Back In (Cambridge: Cambridge University Press, 1985) "