Thanksgiving, unique among all the other official holidays of the American republic, calls back to 1621, before the revolution.
The holiday has explicitly religious origins. Although contemporary multiculturalists tend to vacillate between portraying the holiday as a celebration of tolerance and decrying the pilgrims for their white, cis-hetropatriarchal Christian fascism, the older spirit of the holiday as a religious feast day tends to fall through the cracks.
As Lincoln himself said when establishing the holiday:
I do therefore invite my fellow citizens in every part of the United States, and also those who are at sea and those who are sojourning in foreign lands, to set apart and observe the last Thursday of November next, as a day of Thanksgiving and Praise to our beneficent Father who dwelleth in the Heavens.
Previously, various presidents including Washington had proclaimed national prayer days within the same date range, more explicitly to proffer prayers in thanks to God.
In modern schools, a typical Thanksgiving day assignment is to instead direct children to write essays thanking their family members for mostly material things, which is deeply contrary to the spirit of prayer. In effect, we encourage children to pray to mundane family members rather than to a sacred deity.
We should note that the Wampanoag tribe that participated in the first Thanksgiving were, in less than a century, nearly exterminated by a combination of disease and war. The surviving men of the tribe were sold into slavery in the Caribbean. This mostly happened after relations between the colonists and the local tribes had broken down over a period of years, and the Indians sparked a war that they had no hope of winning.
Thanksgiving has always been something of a revisionist holiday, imposed by the Union before the Civil War had even ended, and even then intended to appeal to the common Christian religion of the warring sides. That the celebrated feast only marked a temporary pause in hostilities between mutually opposed populations seems to be little remarked upon.
The Thanksgiving holiday is less a real tradition and more of an artificial one which nonetheless hooks into Autumnal harvest festivals which are common in farming societies throughout the world and throughout history. Many of the vegetables and the centerpiece turkey, are native to the United States, so the holiday’s specific form isn’t readily transferable outside the continent.
The war after the first Thanksgiving
This Thanksgiving, remember the doughty settlers who achieved victory over the savages in King Philip’s war, in a strange land separated from home by a perilous ocean journey.
The natives, far from being victims of perfidious trickery, were victims of their own bad political judgment, according to this short history of King Philip’s war by George Bodge:
The Court at Plymouth itself had interfered and forbidden the transfer of certain parts of the Wampanoag territories, and thus doubtless saved the Indians in various tribes a home. Pokanoket, the hereditary home, was thus saved to Philip’s people ; and here he lived at the time of the opening of the war. This place was called by the English “Mount Hope,” and it is now embraced in the town of Bristol, R. I. 
50 years after the first Thanksgiving, the natives were actually being protected by the colonial government from their own incapacity to preserve their hereditary lands. There were multiple reasons for this, both material and spiritual.
In some of the plantations, the settlers purchased their lands of the Indians, as a matter of precaution ; partly that they might have that show of title in case any other claim should be set up in opposition to theirs, and partly to conciliate the savages, whose hostility they feared, and whose friendship was profitable in the way of trade, in furs and other products of the hunt. The Indians were always at disadvantage with the English, in all the arts of civilized life. The English paid no heed to Indian laws or customs or traditions; and ruthlessly imposed their own laws, customs and religious ideas, with no apparent thought of their intolerance and injustice. They made treaties with the savages in the same terms which they would have used had they been dealing with a civilized nation.
Further, the Pilgrims believed that it was their sacred obligation to save the immortal souls of the natives. More than the purchase of their lands, attempts at conversion were what would tend to provoke violence from the tribes more than anything. But that motivation was also what encouraged the Puritans to preserve those tribes from their natural diminishment in the face of a vastly superior civilized competitor.
In a twist that ought to be entertaining to modern readers, another cause for war was the common demand made by colonist to Indian law-breakers to give up their firearms. Given that their firearms were often among their most prized possessions, the tribesmen would often turn to rebellion rather than give up their guns.
The conflict came to a head when the pilgrims exposed a plot by the Wampanoag and allied tribes to simultaneously ambush all of the European settlements in the area, which, if they’d been successful, might have annihilated New England. ‘King Philip,’ whose real name was Metacomet, the chief of the Wampanoag, was not ultimately able to unify all of the tribes in the area in a timely fashion. The exposure of the aggressive plot, combined with sporadic raids on settlements, gave all the motivation that was necessary for the English settlers to organize a series of military campaigns to neutralize the threat posed by the native raiders.
A particular turning point in the war occurred when the Nipmuck Indians, who had been negotiating for peace, instead decided to ambush the Plymouth delegation, killing many, forcing them to withdraw to a fortified position in the forest where they had to defend themselves from the onslaught for days.
Part of what made peace so difficult to achieve without conflict was that the Indians were out-matched in terms of combat effectiveness, even if both sides has similar armaments, and the colonists were out-numbered. This pushed them to use hit and run methods, deceptions, their knowledge of the terrain and other stratagems to create local advantages in battle.
The natives were also split into numerous tribes, whereas the colonists were unified by ethnicity, culture, and religion. Further, although the colonists were not as disciplined or renowned as Oliver Cromwell’s New Model Army, they were cut from the same stock, and were formidable fighters. Furthermore, many of the colonists of that time had in some cases served under Cromwell or were the direct descendants of participants in the English civil war.
The Indians were not the cuddly sacred-victims as we know them today: they succeeded in destroying Springfield, Warwick, and numerous other forts and settlements, often carrying away women and children as slaves or otherwise burning them alive. These atrocities only incensed the fervor of the colonists more.
Over time, attrition of the native leadership, combined with the diplomatic failure of the native raiders to unify the New England tribes, lead to their defeat. Without the capacity to manufacture ammunition of their own, and cut off from the European trade that had provided their armaments, defeat became certain:
The remaining operations of the war in these parts were simply the hunting down of almost defenceless enemies. The colonial authorities issued a proclamation, calling all those Indians who had been engaged in the war to come in and surrender, submitting themselves to the judgment of the English courts. Many parties sought to take advantage of this, but were captured upon their approach by scouting parties, and treated as captives. Some of those who had been prominent in the war and could not hope for mercy, escaped to the eastward and put themselves under the protection of Wannalancet and his Pennacooks, who had remained neutral. Some fled further to the east, and there incited war.
‘King Philip’ was eventually betrayed and killed, which put an end to the main conflict, although raids would continue for generations after.
Stop feeling guilty about all those dead Indians
Today, Americans have developed a guilt-complex about the native wars and the conquest of the continent. In some ways, this is understandable: the settlers, by and large, didn’t want to exterminate the Indians. They wanted to convert them to Christianity. Wherever the Indians did not convert, there had to be implacable conflict, because those natives who retained their culture did not respect the authority of colonial law. For this reason, it was difficult to mediate disputes between Christians and natives, because they did not share a common moral framework.
In a sense, the guilt inculcated into American young people is motivated by regret, that the great conversion project in America did not really succeed to the extent that it did in South America, where the Catholic Church had far more success, even when there were countless wars between the conquistadors and the native empires. Even though the liberals of today would never express it like that, there is a sense of malaise, that relations between the settlers and the natives could have had more peaceful ends.
Increase Mather, the father of Cotton Mather, (if you ever find yourself asking ‘who were the Boston Brahmins,’ well, you could start there), also wrote a contemporary history of the war . Increase was explicit in describing the motivation of the Protestant settlers to compete with the Catholics in making conversions far to the south:
It troubleth me, when I read how the Papists glory in that they have converted so many of the East and West Indians to the Christian Faith, and reproach Protestants because they have been no more industrious in a work of that nature. Though I know they have little cause to Glory, if the whole truth were known. For as for many of their Converts, inasmuch as they are become Vassals, not only to the Heresies, but to the Persons of those who have Proselyted them, they are as Christ said concerning the Proselytes of the Scribes and Pharisees, twofold more the Children of Hell, then they were before; and many of them know little of Christianity besides the Name. Witness the celebrated Story of that Franciscan, who wrote a Letter to a Friend of his in Europe, wherin he glorieth that having lived six and twenty years amongst the Indians, he had converted many thousands of them to the Faith…
Mather notes that the war was sparked by the murder of an Indian convert to Christianity by other Indians who were themselves still heathens. That man, John Sausaman, had even translated sections of the Bible into the native language.
Today, we still see echoes of the founding stock of America — Mather called Plymouth the English Israel, and today many Americans, especially conservatives, will declare that America stands with Israel as currently constituted, and still treats prophecies about the redemption of Israel (the physical place) as both spiritually and politically necessary.
What we no longer see is the level of human quality demonstrated by both Mather and his popular readership, whom he expected to be able to understand passages of Latin, Greek, and Hebrew with fluency. The sort of man who will go to die by the score in the swamps has also become sparse, especially in the greater Boston area.
One could also say that, in war, there were misunderstandings between what was acceptable and what was not. England had been unusual among European countries in terms of the high level of civilized behavior expected among belligerents, moreso even than the rest of Europe. Indian practices like the killing of wounded people and the ambushing of surgeons, which were ordinary to their raiding war-methods, seemed barbaric to the English, and further provided moral justification for the war.
Mather reports that, in one case, when several English troops were captured:
For they stripped them naked, and caused them to run the Gauntlet, whipping them after a cruel and bloudy manner, and then threw hot ashes upon them; cut out the flesh of their legs, and put fire into their wounds, delighting to see the miserable torments of wretched creatures. Thus are they the perfect children of the Devill.
Condemning the actions of the American colonists in war is moral idiocy
It’s only thanks to the security provided by the victory of those Puritans that provides the luxury to moralize about what they did, to judge them as evil, for defending themselves from Native aggression. The scale of the defeat of the tribes was only so great because those same tribes made peace almost impossible to gain and maintain.
The Puritans were willing to give the Indians the ancient justice of eye-for-eye and tooth-for-tooth. Whereas the settlers had been burned in their farmhouses with the women and children, so did the Army to the Indians in their wigwams. When the Army found an Englishman who had converted to the Indian side, in Mather’s words, he was caught and executed.
In the Thanksgiving story as told today, the Puritans were proto-hippies, sharing because they cared. In actual history, they were the hardest, most righteous killers on the continent. That’s why we’re here, and the people whom they defeated live in trailers on reservations. We’re here to celebrate Thanksgiving thanks to the victorious English infantry who, under conditions so difficult that the modern mind struggles to understand, triumphed in an alien land against an implacable and wily enemy, over a period of years.
When they gave Thanksgiving, it was for victory:
June 29. Was observed as a day of publick Thanksgiving to celebrate the praises of that God, who that begun to answer Prayer. And although there is cause for Humiliation before the Lord, inasmuch as the Sword is still drawn against us, nevertheless we are under deep engagement to make his praise glorious; considering how wonderfully he hath restrained and checked the insolency of the Heathen.
We have traded this righteous mentality for one of flagellation, of permanent guilt for a war conducted on just grounds — certainly more just grounds than the liberals of today, who attack their Puritan forebears, use to justify their various inane foreign wars.
 “A Brief History of King Philip’s War” by George Bodge, 1891
 “A Brief History of the Warr With the Indians in New-England” by Increase Mather, 1676