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Alliance Treaties and the Political and Legal Order of Old Regime Europe

By: Randall Lesaffer

Alliance treaties, like peace treaties, formed significant threads in the fabric of the political and legal order of Old Regime Europe. The ability to draw on the diplomatic, financial, economic and military support of friendly powers was as much a determinant for security in peace and victory in war as the ability to extract resources from one’s own territories and colonies. Since the sixteenth century, and ever since, most great power wars have started as or evolved into coalition wars that pitted alliances of greater and smaller powers against one another, or at least a coalition against a great power. They have also become, and remain, a mode – benign or less so – of organising and managing power hierarchies among sovereign states.

Early-modern alliance treaties were, in terms of their design and contents, of a highly political nature and were less standardized and legalized than peace treaties. Nevertheless, over time, some fixtures developed, making these treaties also part of the general lore, customs and laws of war- and peace-making in particular, and of the ‘public law of Europe’ in general in Old Regime Europe.

In the Nine Years War (1688–1697), France under Louis XIV (1638–1715) and a very few minor allies were pitted against the so-called Grand Alliance, led by the Austrian Habsburg Monarchy under Emperor Leopold I (1640–1705), the British Monarchy and the Dutch Republic. By 1689, the last two powers were effectively ruled by William III of Orange (1650–1702). 

The Grand Alliance structurally rested on two pillars, that were forged together by the Treaty of The Hague of 12 May 1689 (18 CTS 367), and subsequent accessions to that treaty. The first pillar was the coalition of German states, including the Kings of Spain and Sweden, who both ruled territories within  the Holy Roman Empire, under the leadership of Emperor Leopold I, known as the League of Augsburg (6 July 1686, 18 CTS 21). This alliance, which provided for the raising of a 60,000 men army and a joint command structure, was a countermove against French incursions and annexations against the Empire, including the Spanish Netherlands, since the Peace of Nijmegen (1678–1679). It actually intended to role back French advances to the borders that had been agreed at the Peace of Westphalia (1648) and the Peace of the Pyrenees (1659), and to reclaim cessions made  to France under the Peace of Aachen (1668), the Peace of Nijmegen (1678–1679) and the twenty-years Truce of Regensburg (1684).

The alliance network of the Dutch Republic with Protestant powers, that William III had made after the French invasion of the Northern Netherlands in 1672, formed the second pillar under the Grand Alliance. Its backbone during the Nine Years War became the close bonds between the British Monarchy and the Dutch Republic, but the Protestant alliance also included, among others, Sweden, Denmark and Brandenburg-Prussia. The major treaty between The Hague and London was the Treaty of Whitehall of 24 August 1689 (18 CTS 485), which renewed the Treaty of Westminster of 3 March 1678 (14 CTS 311).

The two pillars were joined together by the Treaty of The Hague of 12 May 1689 between Emperor Leopold I and the Dutch Republic. The treaty provided for the accession of the British Monarchy under William III and the Spanish Monarchy under its last Habsburg king, Charles II (1661–1700) (Art. 10). The British Monarchy acceded on 20 December 1689; Spain followed on 6 June 1690. Later Savoy, Brandenburg-Prussia, Bavaria, Mainz, the elector and dukes of Brunswick-Luneburg, Saxony, Cologne, Lorraine and Münster also joined, as did the Swabian and Franconian Circles of estates of the Empire. The treaty was renewed in 1695.

The Hague Treaty of 1689 formed the linchpin of the alliance structure. It was a political treaty that set out the goals and major principles of the cooperation, but held few details about the actual contributions or the effective organisation of the joint war effort. This was taken care of by the pre-existing alliance treaties and later wartime treaties and executive agreements between commanders and diplomats. Taken together, the treaties that constituted the Grand Alliance offer a good example of the lore and customs of alliance treaty-making.

Alliance treaties could either be made in times of peace, or after war had erupted. The League of Augsburg was made before formal war was declared between France, the Austrian Habsburgs and the Holy Roman Empire; the Treaty of The Hague of 12 May 1689 was signed after open rupture had occurred between France and the Republic.

Alliances were distinguished between defensive alliances and alliances that were both defensive and offensive. The first sort was by far the more frequent; the second sort was very rare in times of peace. Whether an alliance was defensive or rather offensive hung together with the definition of its casus foederis, the circumstances and goals that triggered and governed the alliance. A defensive alliance shielded against an attack or invasion by a third power. A treaty could be intended to protect against any power, but could also restrict the protection of the alliance to a given power or exclude particular powers, such as pre-existing allies or powers with which one of the allies was already at war. An offensive alliance was always targeted against a particular power and generally included a definition of what territories or rights the allies demanded from the enemy. It entailed a promise to continue the joined efforts and the war until these goals were met.

The League of Augsburg was labelled a defensive alliance (Art. 2), although it actually provided for the retaking of all territories which France had acquired, through illegal incursions but also through later treaty cessions, after the Peace of the Pyrenees. The underlying argument was that all French expansions since 1659 were consequential to French aggressions, starting with Louis XIV’s invasion of the Spanish Netherlands in 1667. The Hague Treaty of 12 May 1689 was literally styled defensive as well as offensive (Art. 2). The preamble referred to the ‘last French invasion, and the unconstant faith of the French in the observance of treaties’ that made the union between the allies necessary for the ‘public peace and safety’ of Europe. Again, reference was made to the execution of the Peace of Westphalia and the Peace of the Pyrenees as the goal of the war, thus defining what territories should be demanded and taken from the enemy. The Anglo-Dutch Treaty of Whitehall of August 1689 was defensive. It guaranteed mutual protection for all existing lands but also ‘rights, franchises and liberties’ of the two states, but limited to Europe.

Alliance treaties often opened with a declaration of ‘friendship’, ‘union’ or ‘good correspondence’. Under these terms, the old treaty-law conception of amity (amicitia) was caught. Amity as a legal concept referred to a positive qualification of peaceful relations between states, whereby they committed themselves to foster one another’s interests and not to commit or allow any harm against the friendly state (Treaty of The Hague, Art. 1).

A provision that was included in virtually all alliance treaties was a prohibition to negotiate about truce or peace, or conclude a truce or peace with the enemy separately, without the knowledge, agreement and/or concurrence – that is participation – of the other members of the alliance. The clauses did not always make very clear what was exactly implied, but it was undebatable that any serious negotiations could not be held secret and no agreements could be made without the consent of allies. The Treaty of The Hague realistically demanded ‘good faith’, thus leaving room for preparatory discussions with the enemy (Art. 5).

In case of an attack or threat of an attack against an alliance member, its treaty parties first had an obligation to intervene diplomatically and put pressure on the offender to stop these hostile actions or threats. The League of Augsburg imposed a duty on its leader, the emperor, to take the initiative. It provided for a meeting of deputies of the members of the alliance to take joint action to exhort the enemy to cease and to ensure compensation for any damages done (Arts. 3–4).  

Early modern European law and diplomatic practice made a distinction between support to an ally as a full belligerent or as an auxiliary. In the former case, an alliance treaty obliged a treaty partner to declare open war upon a third power that attacked another member of the alliance. In the latter case, the treaty partner’s obligation was limited to the number of troops and ships or the financial subsidies that had been provided for in the alliance treaty. 

The Treaty of Westminster of 1678 between London and The Hague interestingly left a choice for the victim of the aggression between open rupture and aid as an auxiliary in case of attack. Articles 5 and 6 laid an obligation on the treaty party to break relations and declare war against the invader within two months after the aggressed partner requested it. During these two months, the ally would, however, be under an obligation of diplomatic intervention with the enemy, and of rendering the military and maritime aid that was to be agreed upon under the alliance. After these two months, the aggressed party would have a choice whether the ally would indeed declare open war or continue to render support as an auxiliary. In the latter case, the ally would not become a full belligerent and would not need to make a new peace treaty with the enemy, nor would general war measures be taken against the enemy, such as disruption of trade, arrest or expulsion of enemy subjects or confiscation of enemy property. 

When war erupted in March 1689 between France and the Republic, and then two months later between France and the British Monarchy, the allies of 1678 made several agreements to renew and strengthen their bonds. Some days before the British declaration of war against France, a treaty was made (9 May 1689, 18 CTS 345) that provided for putting a certain number of warships to sea that would operate together. On 22 August, two days before the formal renewal of the 1678 alliance, a convention was signed at London that committed both parties to sever all commercial ties with France and forced the same on all other belligerents against France. It also held regulations with regards to neutral trade with France (18 CTS 479).


The full text of the 1678 Treaty of Westminster is printed in A General Collection of Treatys, Declarations of War, Manifestos, and other Publick Papers, vol. 1 (London: J. Darby 1710).

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