 Taking advantage of this, the Mantineans decided to unify their settlements into a single city, and to fortify it; a decision which greatly angered Agesilaus.Furthermore, Tegea, supported by Mantinea, instigated the formation of an Arcadian alliance.This led to the Spartans declaring war on Mantinea, whereupon the majority of Arcadian cities grouped together to oppose the Spartans (thus forming the confederation that the Spartans were trying to prevent), and requested assistance from the Thebans.