The Triforce of Peace is arguably the most powerful triforce there is. Most people agree that it's also the most useless triforce there is.
In the late 1960s, Joseph Harkinian, then the king of Hyrule, became a hippie, complete with the typical obsession with ending conflicts. He tasked Hektad and others with creating a triforce that would prevent people from fighting other people. The project was finally completed in early 1976, and Joseph immediately used the Triforce of Peace on himself. The triforce then performed a foolproof procedure that ensured Joseph would never get in a fight again; it killed him. That counts as a success, right?
Pretty much nobody has ever tried to use the Triforce of Peace again. Even Ganon thinks something that can make people die so easily is too boring. Still, just to be safe, Joseph's successor sent it to Daiastan, and from there it was sent to Potland, where it was buried somewhere. It's remained there, undisturbed, ever since.