In 266 BCE, the armies of Emperor Antigonus II Gonatas laid siege to Megara, hoping to seize the small, but wealthy, city's harbours. The contest was, at first glance, hopeless: Antigonus's armies were much larger and backed, moreover, by phalanxes of battle-elephants. Faced with certain defeat — the ancient military historian Poluainos recorded in his classic, Strategems in War — the Megarans hit upon a tactic of considerable genius.