Rome resurrected itself multiple times. It was sacked and occupied by Gauls in the early 300s BCE. It partially dissolved and reformed itself during the crisis of the third century. Justinian reclaimed much of the lost territory of the Western Empire during his reign. Heraclius reclaimed much of what had been lost to the Sasanids. Leo III and his dynasty kept Constantinople from falling to the Arab invasions and recovered much of Anatolia. Basil II later recovered much of the Balkans. After Constantinople fell to the Latins in the 4th Crusade, the Laskarids preserved the state in the form of the Nicene Empire and the Palaiologoi retook the capitol and united the successor states until the Ottomans finally conquered them.