You are both correct. The first Thanksgiving was celebrated by pilgrims who left England to have religious freedom. The original Thanksgiving was a celebration of a safe arrival (for the survivors), a bounteous harvest and new Native American friends. It was also a remembrance of those they lost on the journey.

>Kicked you out? Hang on - Thanksgiving happened a long time before independence.
>Wasn't it the British that first celebrated that :-}
>
>You've got July 4th. for the other bit.