Sure, Thanksgiving may seem like it goes on for days -- even weeks, once Uncle Johnny gets into the Wild Turkey and Aunt June takes out her dentures to slurp down some pumpkin pie -- but the first celebration actually lasted for three whole days.
While the event was indeed intended to toast the successful harvest, it also marked solidified relations among the Pilgrims and the Wampanoag Indians. Earlier that year the two sides signed a mutual protection pact, providing that both peoples would leave each other be and act as allies in defending against any attack on either group [source: Plimoth Plantation].
Squanto, a Patuxet Indian who was captured and shipped to England as a slave before returning to North America and taking up with the Wampanoag, helped the Pilgrims endure their first year in New England by teaching them survival skills. He also negotiated the treaty on behalf of the tribe. Plymouth Colony governor William Bradford and Wampanoag Chief Massasoit eventually sealed the deal in March of 1621 [sources: Plimoth Plantation, American Indian College Fund].
Most of what is known about the first Thanksgiving celebration comes from a letter Edward Winslow, an early Pilgrim leader, later wrote to a friend describing the event. As Winslow explains it, "for three days we entertained and feasted." Experts believe they probably also sang, danced and played games [sources: Walker, Plimoth Plantation].
This fun and games didn't last forever though. After decades of peace, relations between the Wampanoag and English settlers eventually deteriorated, culminating in a war between the tribe and colonial forces in 1675 [sources: Pilgrim Hall Museum, National Museum of the American Indian].