Demetrius then went to Greece, and tried to overthrow Cassander, but the other kings joined against him, and he was obliged to go home, for Seleucus was threatening Antigoneia.  Antigonus and Demetrius collected their forces, and fought a great battle at Ipsus, where Seleucus brought trained elephants from India, which had lately begun to be used in battle, and were found to frighten horses so as to render them quite unmanageable.  Demetrius, however, thought he had gained the victory, but he rushed on too fast, and left his father unsupported, so that poor old Antigonus, who was eighty years of age, was shut in by the troops of Seleucus and killed.  Demetrius had to retreat to Ephesus with his broken army.