The great shift in alliances called the Diplomatic Revolution led directly to the outbreak of the official war in Europe for seven years, which actually began in the British colonies and then joined Austria against Prussia in 1740 AD, and the most dramatic step of the diplomatic revolution was that France joined its enemy the Habsburg family in Austria.

In 1755 AD, the British touched on this diplomatic revolution in order to employ a second force in the task of defending Hanover, and they reached a treaty with Russia, which took a small part in the War of the Austrian Succession as an ally of England, and the Anglo-Russian treaty raised the concern of Frederick the Great, and in January 1756 AD , the Prussian king concluded an alliance with Britain between England and Prussia, isolating France and giving the Austrian chancellor the opportunity he had been waiting for.

Austria needed to take revenge on him and take back Silesia who was an ally of Frederick's army, and this required an alliance with France, not Britain, and the last act of the diplomatic revolution occurred when Russia joined the Franco-Austrian alliance. The new war, like its predecessor, was actually two separate wars - one Continental, marine and colonial.

In the European campaigns of the Seven Years' War, Frederick faced the powers of Austria, France, and Russia, whose combined population was fifteen times greater than that of Prussia, and Frederick had almost no allies except Britain, which gave them financial support and little actual military aid, and to fill the ranks of his depleted army. , he violated international law, and since British subsidies covered only a small part of the war's expenses, he seized Saxon, Polish, and Russian coins and melted them down for use.

The last factor in saving Prussia was the coalition rocking against it, Russia's generals were unexpectedly frightened, and moreover the French, the most powerful of the Allies, had to fight a war on two fronts in Europe and abroad without the financial resources to do both, and the great alliance that Created by the Austrian Chancellor Prince von Konitz (1711-1794), to the extraordinary degree of friction, mistrust, and cross-purposes of wartime alliances.

When Elizabeth of Russia (reigned 1741-1762) died in January 1762, she was succeeded by Tsar Peter III, a passionate admirer of Frederick the Great, who immediately put the forces of Russia at Frederick's disposal, and although he ascended to the Russian throne only until July, His reign marked a decisive turn in the Seven Years' War, and in 1763 AD, Prussia won its war.

Meanwhile, Frederick's British partner was losing abroad, and during the first year and a half of fighting the British suffered setbacks on almost every front at sea losing the important Mediterranean base of Minorca in the Balearic Islands and in North America the British lost time and time again, but the most exciting In the misfortunes of Britain that occurred in India in June 1756, the Nawab of Bengal, allies of the French, held 146 British prisoners in Calcutta in a small room. The incident became known, as an officer of the English East India Company described it, as the Black Hole.

It was William Pitt (1708-1778) who turned the situation in Britain's favour. He strengthened the Anglo-Prussian alliance by sending great subsidies to Frederick and placing the English forces in Hanover under the command of the Prussian commander. He replaced arrogant generals and admirals and took active measures that transformed the naval and colonial campaigns. The Royal Navy defeated both the French fleet in the Atlantic and the Mediterranean in 1759.

Britain controlled the seas, and Britain was able to continue its trade abroad at a prosperous pace, while French foreign trade declined rapidly to one-sixth of the pre-war rate, and the French colonies cut off supplies and reinforcements from France, and the British achieved other victories in the war, which the English colonists described as the French and Indian War, In Canada, the English General James Wolf (1727-1759) took Louisburg in 1758; The following year he lost his life but won immortal fame in a great victory over the Plains of Abraham over Quebec, and when the remaining French stronghold, Montreal, fell in 1760, the French Empire ended.

Although Pete won the war, he did not make peace, and George III (reigned from 1760 AD to 1820 AD) rejected him in 1761 AD and in the Treaty of Paris 1763 AD the French regained their islands in the West Indies, which are considered highly valued as a major source of sugar, Whereas British farmers in the Caribbean were relieved that their markets had been flooded with sugar from the French islands captured during the war.

France, however, lost all of its possessions on the North American mainland, and Britain gained both Canada and the disputed territories between the Appalachians and Mississippi. Moreover, Spain, which joined France in 1762 when the war was already hopeless, ceded to Britain the peninsula which East Florida and the coast of the Gulf of Mexico are called in compensation

France gave Spain the city of New Orleans and the vast territory of Louisiana west of the Mississippi, and in India, France regained its possessions on the condition that it not fortify it, for Britain the Seven Years' War marked the beginning of an almost complete rise in India; For France, it marked the hypothetical end of the "Old Empire".