Babylonian War The Babylonian War was a conflict fought between 311 - 309 BC between the Diadochi kings Antigonus Monophthalmus and Seleucus I Nicator , ending in a victory for the latter . The conflict ended any possibility of restoration of the empire of Alexander the Great , a result confirmed in the Battle of Ipsus . Preliminaries . After the death of Alexander the Great on 11 June 323 BC , his empire disintegrated . Officers who were trying to save it were defeated during the First War of the Diadochi . During the Second War of the Diadochi , the power of Antigonus Monophthalmus , who had created a state of his own in Anatolia and Syria , was growing ; this caused alarm among the other generals , but in the Third War of the Diadochi , Antigonus managed to keep Ptolemy I Soter of Egypt and Cassander of Macedon in check . In December 311 , the warring parties concluded the Peace of the Dynasts , and recognized each other . The only ruler who was excluded , was Seleucus I Nicator . Antigonus had expelled this satrap from Babylonia in 316 , but Ptolemy had given him an army , which he now used to return to his satrapy . Campaigns . Seleucus , reinforced with Macedonian veterans from Harran , reached his former capital Babylon in the second half of May 311 . He was soon recognized as the new ruler . Only the fortress remained occupied by a garrison loyal to Antigonus . Seleucus now built a dam in the Euphrates and created an artificial lake ; in August , he suddenly broke the dam , and a flood wave destroyed the walls of the fortress . Antigonus ' satraps in Media and Aria , Nicanor and Euagoras , now decided to intervene with an army of 10 , 000 infantry and 7 , 000 horsemen , but Seleucus and an army of 3 , 000 infantry and 400 cavalry had been waiting for them near the Tigris since September 311 . By hiding his men in one of the marshes and attacking by night , Seleucus was able to defeat the Macedonian soldiers in the army of Nicanor and Euagoras , after which the Iranian soldiers decided to side with the ruler of Babylonia ( November 311 ) . Without any problems , Seleucus could move through the Zagros Mountains , occupy Ecbatana ( the capital of Media ) , and continue to Susa ( the capital of Elam ) . He now controlled southern Iraq and the greater part of Iran . News of the defeat of Nicanor and Euagoras must have reached Antigonus at about the time of his signing the Peace of the Dynasts ( December 311 ) . He ordered his son Demetrius Poliorcetes to restore order ; he arrived in the early spring of 310 , when Seleucus was still in the east . Although Demetrius managed to enter Babylon , he was not able to cope with the resistance that Seleucus ' adherents were able to organize , and he returned to Syria without having achieved his goal . His father Antigonus tried again in the autumn of 310 , and also managed to enter Babylon , but was forced to leave the city in March 309 . Returning to the northwest , he met the army of Seleucus , who ordered his soldiers to have their meal during the night , attacked Antigonus ' soldiers while they were having breakfast , and won a decisive victory . Significance . Antigonus retreated and accepted that Babylonia , Media , and Elam belonged to Seleucus . The victor now moved to the east and reached the Indus valley , where he concluded a treaty with Chandragupta Maurya . The raja received the Punjab and gave Seleucus a formidable force of five hundred war elephants . By adding all of Iran and Afghanistan , Seleucus became the most powerful ruler since Alexander the Great . Restoration of Alexander ' s Empire was , after the Babylonian War , no longer possible . This outcome was confirmed in the Fourth War of the Diadochi and the Battle of Ipsus ( 301 ) . Sources . Our knowledge is based on Diodorus Siculus , " World History " , 19 . 90 - 93 and 19 . 100 . He discusses Seleucus ' battle against the satraps and Demetrius and offers plausible numbers for the armies , but ignores the campaign of Antigonus . This is described in one of the contemporary Babylonian Chronicles , the Chronicle of the Diadochi ( = ABC 10 = BCHP 3 ) , which also offers the chronological framework . Since the publication of this cuneiform tablet , now in the British Museum , our understanding of this conflict has much increased .