Anglo - Prussian alliance ( 1756 ) The Anglo - Prussian Alliance was a military alliance created by the Westminster Convention between Great Britain and Prussia which lasted formally between 1756 and 1762 during the Seven Years ' War . It allowed Britain to concentrate the majority of its efforts against the colonial possessions of the French - led coalition , while Prussia bore the brunt of the fighting in Europe . It ended in the final months of the conflict , and despite its end , strong ties between the two remained . Creation . Since 1731 Britain had been tied to Prussia ' s major rival Austria by the Anglo - Austrian Alliance . Prussia had been allied to Britain ' s enemy France . Following the War of the Austrian Succession during which she has lost the valuable province of Silesia , the Austrian Empress Maria Theresa tried to gain British support for a proposed military action to reclaim it . When the British government refused she grew disenchanted with them - and in 1756 made an alliance with France . Suddenly without a major ally in continental Europe , the British hastily concluded a similar pact with Frederick the Great of Prussia hoping it would forestall a major European war by maintaining the European Balance of Power . Prussia had a number of leading British supporters including William Pitt . In practice . Despite the British hope to avoid a war , Frederick launched a pre - emptive strike against Austria in August 1756 - overunning Saxony and Bohemia . However , he was soon faced with an onslaught of enemies including France , Austria , Sweden and Russia and was forced to retreat . By 1757 it appeared that without substantive British assistance - Prussia was about to collapse . Frederick had established a large and well - disciplined army - but it was continually short of money . The British began to send large financial subsidies to support their ally . On 11 April 1758 the two states concluded the Anglo - Prussian Convention formalising their alliance . Neither side would make peace without consulting the other . Following the occupation of Emden , a British contingent was despatched to the continent to serve with the Duke of Brunswick , a Prussian ally - and they served to shield Frederick ' s western flank - allowing him to focus in other directions . Under Prussian pressure , the British - backed Hanoverian government repudiated the Convention of Klosterzeven and re - entered the war on Prussia ' s side . In spite of British aid the Prussian war effort still nearly collapsed in 1759 - despite an Allied victory at the Battle of Minden . However from then until the end of the war , events turned largely in the favour of the Anglo - Prussian Allies . Britain had enjoyed an Annus Mirablis in 1759 defeating France in Europe , North America and Asia as well as repelling a planned French invasion . Britain won a number of key victories over Spain during 1762 , and the Russian Empress died - leading them to withdraw from the war against Prussia . Collapse . It was eventually dissolved in 1762 when Britain withdrew financial and military support for Prussian war aims in Continental Europe . Britain won more favourable terms at the Treaty of Paris , gaining a number of the colonial possessions they had captured from France and Spain . Prussia was able to retain Silesia , but did not achieve the acquisition of further large territories it had hoped for at the outbreak of war . The two powers made distinctly separate peace agreements to end the war . In the years after the war , their relationship deteriorated - with Prussia rejecting approaches from Britain to form a similar alliance before and during the American War of Independence . Prussia instead concluded a fresh alliance with Russia in 1764 while Britain remained diplomatically isolated . In the 1780s , after the American War , Britain and Prussia began to move closer again . They co - operated during the Dutch Crisis and the following year formed part of a Triple Alliance with the Dutch Republic . Following the outbreak of the French Revolution Britain and Prussia both took part in the various coalitions formed against France .