378 BCE

A Spartan attempt to seize Piraeus brings Athens closer to Thebes. The Athenian mercenary commander Chabrias successfully faces off the larger army of Agesilaus II near Thebes. At the advance of Agesilaus' forces, instead of giving the order to charge, Chabrias famously orders his men at ease—with the spear remaining pointing upwards instead of towards the enemy, and the shield leaning against the left knee instead of being hoisted against the shoulder. The command is followed immediately and without question by the mercenaries under his command, to be copied by their counterparts beside them, the elite Sacred Band of Thebes under the command of Gorgidas. This "show of contempt" stops the advancing Spartan forces, and shortly afterwards Agesilaus withdraws. The Servian Wall is constructed around Rome to prevent the city from being captured or sacked (see 390 BC). This is the first fortification that the Romans build around their home city. Athens allies itself with Thebes and forms the Second Athenian League. The confederacy includes most of the Boeotian cities and some of the Ionian islands.

In the 370s BC, the 4th century BC.