Archelaus had let his men relax after taking their positions, while Sulla had set his men to work building trenches that he hopes will cut Archelaus' cavalry off from the plains and move the fighting to more boggy areas.
Archelaus, recognizing Sulla's strategy, launches several attacks on the workers and the soldiers sent to protect them.
In one of these, Archelaus' stepson Diogenese distinguishes himself in a valiant attack where he dies gloriously.
In Archelaus' final attack, Sulla routs his troops and carries his camp.
Plutarch says that so many men died that the marshes ran with blood, and almost two hundred years later weapons will still be found sticking out of the marshes.
After the battle, Sulla destroys three Boeotian towns: Anthedon, Darymna, and Halae.
Later, upon meeting fisherman from Halae who gift him fish, Sulla tells them he is surprised there are any of them left, but lets them go and tells them not to worry.
As a result of this incident, the people of Halae are inspired to repopulate their town.
While Sulla is away fighting Mithridates, Rome is suffering from civil disorder at the hands of the two consuls of 85 BCE, Cinna and Carbo, prompting eminent members of society to flee to Sulla's camp, including his wife Metella and their children.
Sulla tries to use his victory at the Battle of Orchomenos to bring about peace with Mithridates so that he can return home, and though Sulla's peace terms are not immediately accepted, Archelaus eventually manages to broker a peace between Sulla and Mithridates.
