That's because Augustus Caesar has his navy unopposed, has his legions online, has his ballistae online, and is ready to REVENGE! on Leonidas.
Cumae, ever the redoubt, is being held down 300-style by a single legion, chilling as a horde of Spartans dash themselves on the rock. Troops are wet in the Adriatic and the Med. This is a serious development for Leonidas, who let this problem fester.
Augustus still might take a white peace: you can see he's still fighting Portugal (combat damage at left.)