As for the reason why the Thebans withdrew from Laconia, most writers say that it was because winter storms came on and the Arcadians began to melt away and disband; others, because they had remained there three entire months and thoroughly ravaged most of the country;
Edition :
Plutarch Lives V: Agesilaus and Pompey, Pelopidas and Marcellus, Ed. Jeffrey Henderson, trans. Bernadotte Perrin (The Loeb Classical Library 87), Harvard University Press: Cambridge/MA - London 1961 (first ed. 1917).
Remark :
motive: Because Epaminondas can't get Agesilaus II. to fight with him, he continues to devastate the country.