The War of Jenkins' Ear  was a conflict between Britain and Spain lasting from 1739 to 1748, with major operations largely ended by 1742. Its unusual name, coined by Thomas Carlyle in 1858, refers to an ear severed from Robert Jenkins, a captain of a British merchant ship. There is no evidence of the stories that the severed ear was exhibited before the British Parliament. The seeds of conflict began with the separation of an ear from Jenkins following the boarding of his vessel by Spanish coast guards in 1731, eight years before the war began. Popular response to the incident was tepid until several years later when opposition politicians and the British South Sea Company hoped to spur outrage against Spain, believing that a victorious war would improve Britain's trading opportunities in the Caribbean. Also ostensibly providing the impetus to war against the Spanish Empire was a desire to pressure the Spanish not to renege on the lucrative asiento contract, which gave British slavers permission to sell slaves in Spanish America. The war resulted in heavy British casualties in North America. After 1742, the war was subsumed by the wider War of the Austrian Succession, which involved most of the powers of Europe. Peace arrived with the Treaty of Aix-la-Chapelle in 1748. From the British perspective, the war was notable because it was the first time that a regiment of colonial American troops  was raised and placed "on the Establishment" - made a part of the regular British Army - and sent to fight outside North America.
Question: How many years did the War of Jenkins' Ear last?
Answer: 9