The ara pacis was dedicated for what historical event?

The Ara Pacis Augustae (Latin, "Altar of Augustan Peace"; commonly shortened to Ara Pacis) is an altar in Rome dedicated to Pax, the Roman goddess of Peace. The monument was commissioned by the Roman Senateon July 4, 13 BC to honor the return of Augustus to Rome after three years in Hispania and Gaul,[][2] and consecrated on January 30, 9 BC.[3] Originally located on the northern outskirts of Rome, a Roman mile from the boundary of the pomerium on the west side of the Via Flaminia, it stood in the northeastern corner of the Campus Martius, the former flood plain of the Tiber River and gradually became buried under 4 metres (13 ft) of silt deposits. It was reassembled in its current location, now the Museum of the Ara Pacis, in 1938.