In 241 BC, during Aratus' third term as "strategos", the Aetolian League invaded the Peloponnese. Aratus and the Spartan king, Agis IV, agreed to defend the Isthmus of Corinth together, but disagreed on strategy. Agis IV wanted to defeat the Aetolians in a pitched battle. But Aratus wanted to avoid immediate fighting, on the grounds that the Aetolians could only cause limited damage at that time as crops had already been harvested and stored. It is unclear whether this reasoning truly reflected Aratus' thinking, or whether he regretted his alliance with Sparta. It has also been suggested that this was one of the episodes of Aratus' life in which he lost his nerve in military matters.