Still yet another aspect of the history of Thanksgiving, which I admittedly was not really aware of. Apparently, it can be traced further back even than the Pilgrims of America, and may have some roots in medieval Europe itself!
Here is the fascinating link:
Passeth the cranb'rry sauce! The medieval origins of Thanksgiving by Ken Albala Professor of History, Director of Food Studies, University of the Pacific, November 25, 2015