11 November. The feast day of St Martin of Tours (d. 397), a soldier, then monk and bishop and patron saint of France. The middle of November was the time for salting meat slaughtered for winter - there being insufficient feed until the following year. An alternate form is Martlemas; the *mart element = a slaughtered ox or cow. Falstaff is referred to as a martlemas in 2 Henry IV. New wine was also tested at this time.
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.