Complex sentence: Telephus fled back to Athens where the Heraclids were and became a General and Leader of the Heraclids a few years before the death of his Grandmother Alcmene he was the one who was there when she died.
Split into simpler sentences: Telephus fled back to Athens where the Heraclids were and became a General and Leader of the Heraclids a few years before the death of his Grandmother Alcmene. He was the one who was there when she died.