Britain had been at war for even longer than that - she was basically at war with one or other European power for most of the 18th century. The Revolutionary/Napoleonic Wars went on for longer unbroken and probably came the closest, but they were the culmination of a century or more of fighting. Had they known that, the 100 days apart, there would now be a half century or more of peace, that would have astounded the characters of Persuasion more than the idea that there would probably be another war along fairly soon!