(I might have my facts skewed but that’s what I took away from my history classes 20 years ago)
I don't think the typhoid blankets your referring to (at least that's what I assume you meant by "gifts that would harm them") were specifically given on the "first" thanksgiving, but you're absolutely right that it happened. Even if the first thanksgiving was 100% as advertised (which it probably wasn't) then it was a short-lived and tiny amount of human decency in what was otherwise a straight up genocide. Nevermind that the story was more about the natives helping the settlers than vice-versa, so really we're just celebrating the time our victims were nice to us while we were still getting ramped up on eradicating their people
Easy, you just make sure each one goes on about 5 seconds after the last, remember the order, then when the time comes, you weils that spatchula like a legendary warrior wielding his/her trusty sword and don't stop for anything