Seven Years%27 War
The Seven Years' War was fought between 1755 and 1764, the main conflict occurring in the seven-year period from 1756 to 1763. It involved every great power of the time except the Ottoman Empire, and affected Europe, the Americas, West Africa, India, and the Philippines. Considered a prelude to the two world wars and the greatest European war since the Thirty Years War of the 17th century, it once again split Europe into two coalitions, led by Great Britain on one side and France on the other. For the first time, aiming to curtail Britain and Prussia's ever-growing might, France formed a grand coalition of its own, which ended with failure as Britain rose as the world's predominant power, altering the European balance of power.

Q: What major power of the time was not involved in The Seven Years' War?
It involved every great power of the time except the Ottoman Empire