To gratify Austria, the British government proposed Hanoverian support for the election of Maria Theresa’s son Joseph as the next Holy Roman emperor. That proposal foundered on the opposition of Frederick the Great (elector of Brandenburg as well as king of Prussia), whom the other German electors did not dare to antagonize. In 1750 Great Britain acceded to the Austro-Russian defensive alliance of 1746, but without subscribing to the secret clause on Silesia and without obtaining from the two empires a guarantee of the status quo in Hanover.

In 1750 Kaunitz went to France to urge French participation in Austro-Russian plans against Prussia. France, however, was neither ready to resume diplomatic relations with Russia (severed in 1748) nor willing to connive in the destruction of Prussia, a development that would have restored Austria to incontestable hegemony in Germany. By 1753, when Maria Theresa recalled him to Vienna to serve as chancellor, Kaunitz had achieved only a vague atmosphere of Franco-Austrian goodwill.

Meanwhile, the Treaty of Aix-la-Chapelle had done nothing to ease tensions between the French and British East India companies, and in North America relations between the colonists had deteriorated steadily from 1752. By 1754 French aggression in North America had reached a level that the British could no longer ignore. London’s policy, which had been to “let Americans fight Americans,” had resulted in a series of French military victories. British Admiral Edward Boscawen attacked French ships in the Strait of Belle Isle in June 1755, beginning an undeclared naval war between the two countries. Before the British government could declare open hostilities against France, it had to safeguard Hanover. British naval superiority could then be brought to bear while France’s superior land forces in Europe were held in check by some Continental ally of the British.

Defensive alliances

Concerned primarily with Silesia, Austria was most reluctant to become implicated in the Anglo-French quarrel. Kaunitz believed that Great Britain should hire German and Russian mercenaries to defend both Hanover and the southern Netherlands; the latter had served as a launching point for previous Austro-British and Dutch operations against France. The decline of the Dutch as a military force had compromised the defense of the Austrian Netherlands, and Kaunitz was in fact willing to consider ceding the territory to the French in return for help regarding Silesia. Ultimately, the force that Kaunitz was willing to exert against France for the defense of Hanover or the Netherlands was far less than what the British required from him.

Rebuffed by Austria, the British sought a new treaty with Russia, and on September 30, 1755, a preliminary agreement was signed in St. Petersburg by Bestuzhev and the British ambassador, Sir Charles Hanbury Williams. It stipulated that Russia should maintain 55,000 men on the Livonian-Lithuanian frontier so that they could be promptly moved to defend British interests on the Continent if necessary. In exchange, Russia would receive a yearly subsidy of £100,000, a sum that would be increased to £500,000 in the event of an attack. Bestuzhev, assuming that the treaty was aimed at Prussia, was delighted to have British money to spend on his own projects. At the same time, and without Russia’s knowledge, the British were in contact with Frederick the Great. Afraid of Austro-Russian intentions and alarmed at the Anglo-Russian negotiations, Frederick welcomed Britain’s overtures, though the result was unlikely to please his French ally. On January 16, 1756, the Convention of Westminster was signed, whereby Great Britain–Hanover and Prussia agreed to respect one another’s territory in Europe and undertook to jointly resist any invasion of “Germany” by a foreign power. The Austrian Netherlands were expressly excluded from that guarantee.

Seven Years’ War events

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French and Indian War

1754 - 1763

Silesian Wars

1756 - 1762

Battle of Minorca

May 20, 1756

Battle of Plassey

June 23, 1757

Battle of Wandiwash

January 22, 1760

Treaty of Paris

February 10, 1763

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The Convention of Westminster dismayed Bestuzhev and his empress, who had not yet ratified the British treaty. Elizabeth peremptorily informed the British that the common enemy envisaged in the treaty could only be Prussia, and, when the British rejected that interpretation, the whole Russo-British arrangement came to nothing. The French government was no less angry at the duplicity of its one ally, Prussia. The French, hoping to thaw relations with Russia and gain more information about the Anglo-Russian talks, had sent a Scottish Jacobite refugee, Alexander Mackenzie, on a clandestine mission to St. Petersburg in autumn 1755. Mackenzie was acting in the service of le Secret du roi as well as the French foreign ministry, but the chief agents of le Secret in Poland had been kept unaware of his mission, lest they regard an overture to Russia as a betrayal of the anti-Russian line to which they had been dedicated. Mikhail Illarionovich Vorontsov, the Russian vice-chancellor and a persistent enemy of Bestuzhev, received Mackenzie very favourably, and Elizabeth’s indignation at the Convention of Westminster served to accelerate a Franco-Russian rapprochement. In April 1756 the Russians pledged 80,000 men to Austria for an attack on Prussia.

To Kaunitz the Convention of Westminster provided obvious reasons for self-congratulation. It justified his view that the British alliance was no longer worthwhile, and it obliged France to draw closer to Austria for fear of isolation now that Prussia was defecting. Franco-Austrian negotiations—which had been resumed in summer 1755 by Austrian ambassador Georg Adam, Graf von Starhemberg, and the French statesman François-Joachim de Pierre de Bernis, a protégé of Louis XV’s mistress, Jeanne-Antoinette Poisson, marquise de Pompadour—had reached a stalemate in December. The announcement of the Convention of Westminster gave them new impetus, however, and on May 1, 1756, the First Treaty of Versailles was concluded. That pact was a defensive alliance between France and Austria, with either party pledging to send 24,000 men to support the other in the event of attack. Notably, it exempted Austria from any obligation to join in a war against Great Britain.

The Convention of Westminster and the First Treaty of Versailles are generally taken as the constituent factors of the diplomatic revolution, but they did not make war in Europe inevitable. Both being expressly defensive, they might well have had the contrary effect, though Kaunitz at least could see the Austro-French agreement as a step toward enticing France into an Austro-Russian offensive alignment against Prussia. The French conquest of British Minorca, achieved in a monthlong campaign from April 19 to May 20, 1756, did not oblige Prussia to war on the British side and was, of course, no concern of Austria’s.

Frederick the Great had tried, unavailingly, to present the Convention of Westminster as not inconsistent with his French alliance. He had, accordingly, to profess to regard the First Treaty of Versailles as harmless to Prussia, but that treaty was clearly advantageous to Austria and so, indirectly, to Russia. In fact, both Austria and Russia were now massing troops on their frontiers nearest to Prussia. Throughout July and as late as August 20, 1756, Frederick appealed to Maria Theresa for assurances of her good intent toward him, but he received no satisfactory reply. On August 29, 1756, Frederick led his army into Saxony, on the way to Austria’s Bohemian frontier. The motive for Frederick’s decisive action, which started the European war, has been much debated. Was he frightened into a preventive war, intending only to seize what military advantage he could in the face of imminent aggression by Austria and Russia, or did he think that the moment had come for another war of annexation? However much the British were annoyed at the prospect of having to support Frederick if his war went ill, the French were aghast at his action. Whereas they had signed their Austrian treaty in the belief that their hands would be free for the vital war against the British and that they could later choose whether or not to abet an Austrian offensive against Prussia, they now found themselves committed to defend Austria against the unforeseen aggression.