King George’s War, (1744–48), American phase of the War of the Austrian Succession, third and inconclusive struggle between France and Great Britain for mastery of the North American continent.

Though technically at peace between 1713 and 1744, the two colonial powers experienced continual differences over boundaries of Acadia (Nova Scotia) and northern New England as well as control of the Ohio Valley. The war was characterized by bloody border raids by both sides with the aid of their Indian allies. The only important victory was the New Englanders’ capture of Louisbourg, Cape Breton Island, on June 15, 1745. Despite ambitious plans, there was little effective military aid from either mother country. Tired of costly and vain struggle, the warring parties signed the Peace of Aix-la-Chapelle (1748), mutually restoring conquered territory but failing to solve important colonial questions.