- The original Thanksgiving was probably not in November - it was probably in late September or early October, which would have been right after most of the harvest was gathered.
- It was not in 1620 - it was in 1621. The Pilgrims, a strict Calvinist religious group at odds with the church and government in England, arrived on the shores of what later became Massachusetts in November of 1620. The modern celebration of Thanksgiving is actually closer to the date that the Pilgrims first landed than to the date some 11 months later when they celebrated their first successful harvest.
- They landed at about the worst possible time - November in Massachusetts is heading into winter and far too late to plant or grow any crops. Lack of skill and fear of the natives limited the amount of successful hunting they could do. They had neglected to bring equipment for fishing since none of them were fishermen by profession. They had to rely mostly on the remaining supplies aboard the Mayflower to feed them through the winter and into the spring and summer of the next year before they could grow or gather much food. In the first terrible winter, half of them died of a combination of malnutrition and disease. Worried about the possibility of being attacked by the native Wampanoag Indians, they buried their dead in secret to hide their shrinking numbers, and the sick men who could still stand staggered to their feet and assembled with muskets in hand whenever an alarm was sounded. Why did this disaster happen? They had intended to land in early summer of 1620 and immediately plant crops, but their departure (from Holland and England) was delayed repeatedly for a variety of reasons. Their journey across the Atlantic didn't get started until September 1620, and then contrary winds and storms meant that it took 2 months to cross the Atlantic.
- The Pilgrims had virtually no contact with the native Wampanoags during the first winter, except for occasional glimpses of people in the distance scouting out their settlement. The Wampanoags, for their part, didn't know what to make or what to do about the Pilgrims. They had just gone through a disaster of their own. The Wampanoags and other native nations in what would become New England were not unfamiliar with Europeans. For almost 100 years, European ships had periodically cruised off the shore, at first to explore, later to fish, trade, and (much more ominously) raid coastal settlements for slaves. By about 1615, the Wampanoags and other native peoples knew a few basic things about Europeans - they were strange looking, strange speaking people who could make some very impressive and very useful things that the natives could not, such as iron tools, woven cloth, guns, and sailing ships - but they were also dangerously unpredictable. One group could be friendly and interested only in trade, while the group that came the next summer might feign friendship and then suddenly attack a town, grab some of the residents, and take them off never to be seen again. These were the kind of people best kept at a distance. Then, in around 1617 or 1618, an unknown group of Europeans unleashed, probably unintentionally, what was probably the most devastating killing weapon that humans could inflict on other humans until nuclear weapons were invented - epidemic disease against a population that had no history of epidemic diseases. Not just any epidemic disease, either - it was smallpox, one of the worst. It devastated the Wampanoags, killing more than half of their population in a year. The worst-hit towns and villages were totally abandoned, with the majority of the population dying and the survivors going to live in other towns. One of the towns that was completely abandoned was a coastal town called Patuxet. It was at the site of Patuxet, abandoned for about a year, that the Pilgrims landed. It was a good location with a fair amount of land that was clear of trees - what had been the fields of the residents of Patuxet until a little more than a year earlier. It was into this ghost town that the Pilgrims moved for the cold winter of 1620-1621, when it once again became a place of disease and death.
There was another problem - the Wampanoags were traditional enemies of another native nation that lived to the west, in what is now Rhode Island - the Narragansetts. The plague had barely touched the Narragansetts, and they now massively outnumbered the Wampanoags. When the spring of 1621 came, Massasoit, the most powerful sachem or chieftain of the Wampanoags, decided that the newly arrived Pilgrims would be much more useful as allies than as enemies. In return for letting them settle on land that the Wampanoags no longer had the population to farm, the Pilgrims promised to aid the Wampanoags in future conflicts with the Narragansetts or any other enemies. The Pilgrims were also a source of European trade goods that were very valuable to the Wampanoags - especially woven cloth and metal tools of various kinds, which were much more durable and resilient than stone tools.
The first Thanksgiving was celebrated by two groups that did indeed have a lot to be thankful for. By the fall of 1621 the Pilgrims were finally growing plenty of their own food, and the Wampanoags had a new ally to help deter attacks from neighboring nations, as well as a source of trade goods. The atmosphere was probably genuinely happy and festive. The future, of course, would not be nearly as happy, at least not for one of the groups involved.