Mursili is credited with the conquest of the kingdom of Yamhad and its capital, Aleppo, in northern Syria. Ca. 1531 BC, Mursili led an unprecedented march of 2000 km south into the heart of Mesopotamia where he sacked the city of Babylon, bringing an end to the Amorite dynasty of Hammurabi. This raid did not result in any Hittite control over Babylonia, but did result in the emergence of the Kassites as the rulers there. He attacked these two cities for grains and cereals because the clouds from the Thera eruption decreased the amount of wheat the Hittites could produce. 
When Mursili returned to his kingdom, he was assassinated in a conspiracy led by his brother-in-law, Hantili I (who took the throne), and Hantili's son-in-law, Zidanta I. His death inaugurated a period of social unrest and decay of central rule, followed by the loss of the conquests made in Syria.