The very fact that from the crossing of the Hellespont to the descent into the plains of the Indus everything had depended on the person and the will of the Conqueror meant that on Alexander's death the first problem to arise was that of the succession. The rules of succession in Macedonia had never been very strictly defined. Alexander had a half-brother, Arrhidaeus, who could have made an acceptable successor. Until 321 the kings were to remain with Perdiccas, perhaps more in theory than in reality, on Craterus. Craterus, Antipater and Perdiccas formed a sort of triumvirate controlling Alexander's legacy. The death of Perdiccas enabled a new, strong personality to make and appearance, Antigonus Monophthalmus, was in turn to embody the unitary ideal. Antigonus' death on the battlefield of Ipsus marks the final passing of the idea of an empire reviving that of Alexander. That is by no means to say that Alexander's work was totally and finally ruined.