Wiktionary
burying the hatchet
vb. (present participle of bury the hatchet English)
Wikipedia
Burying the hatchet
Bury the hatchet is an American English idiom meaning "to make peace". The 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. Weapons were to be buried or otherwise cached in time of peace.