Aristomachus of Argos, Macedon's only remaining ally in the Peloponnese, bowed to force majeure and finally joined the Achaean League. The following year, 228 BC, he was elected "strategos". That the same year, the alliance between the Achaeans and the Aetolians broke, the only surprise being it had lasted ten years. After Demetrius' death, Antigonus III Doson became regent for the child-king Philip V of Macedon. He secured the northern frontier of his kingdom, and concluded a treaty with the Aetolians in about 228 BC.