To bury the hatchet means to make peace with an adversary.
This American phrase is an allusion to the figurative or literal practice of putting away the tomahawk at the cessation of hostilities among or by Native Americans in the Eastern United States, specifically concerning the formation of the Iroquois Confederacy and in Iroquois custom in general. Hatchets were buried by the chiefs of tribes when they came to a peace agreement.
The first mention of the practice is to an actual hatchet-burying ceremony. Years before he gained notoriety for presiding over the Salem witch trials, Samuel Sewall wrote in 1680, “I write to you in one [letter] of the Mischief the Mohawks did; which occasioned Major Pynchon’s goeing to Albany, where meeting with the Sachem the[y] came to an agreement and buried two Axes in the Ground; one for English, another for themselves; which ceremony to them is more significant & binding than all Articles of Peace[,] the hatchet being a principal weapon with them.”
However, the phrase refers to a much earlier practice, possibly before the European settlement of America. Thwaites’ monumental work Jesuit Relations, 1644, suggests the practice: “Proclaim that they wish to unite all the nations of the earth and to hurl the hatchet so far into the depths of the earth that it shall never again be seen in the future.”
The New England Historical & Genealogical Register for 1870 has the record that Samuel Sewall made in 1680, where he recounts the burying of hatchets by Native American tribes.
References in print that explicitly mention burying the hatchet are somewhat later. The earliest appears to be the History of the Five Indian Nations of Canada, 1747, by someone named Cadwallader Golden.
Do you suppose that was a pen name, or did his mother really name him Cadwallader?