Seven Years War
The Seven Years War from 1756 to 1763 was a near-global conflict involving the major European powers. Great Britain, Hanover and Prussia were ranged against France, Austria, Russia, Saxony and Sweden. It began as a result of general discontent about the terms of the Treaty of Aix-la-Chapelle (1748), which had concluded the War of the Austrian Succession. The main grievance was held by the Austrian Habsburgs. They had lost the mineral-rich province of Silesia to Frederick the Great of Prussia. Aix-la-Chapelle had confirmed Frederick's conquest and the Habsburgs were demanding restoration. Russia had not been a signatory to the treaty but was now alarmed by the growing strength of Prussia, which the Russians saw as a serious threat to their own ambitions in Poland and the Baltic.
Outside Europe, the French and Indian War had begun in July 1754, the fourth North American war between Britain and France since 1689. This conflict was ongoing in 1756 and was a significant contributory factor in the outbreak of the Seven Years War. Anglo-French enmity spread to India where the Third Carnatic War was fought until 1763. Given the global aspect, the Seven Years War per se was essentially a European war.
The European alliances were cemented by the Convention of Westminster (1756) between Britain and Prussia, and the First Treaty of Versailles (1756) between Austria and France.