History of the Peloponnesian War
Thucydides
Thucydides, Vol. 1-4. Smith, Charles Foster, translator. London and Cambridge, MA: Heinemann and Harvard University Press, 1919-1923.
The Eleans, then, becoming angry because they did not vote to go against Lepreum, went off home; but the rest of the allies began to make preparations at Mantinea to go against Tegea; and there were even some of the inhabitants of the town who were in favour of yielding the place to them.
But the Lacedaemonians, on their return from Argos after making the four months' truce, blamed Agis severely for not subduing Argos, when, in their judgment, the happy opportunity was such as had never been offered before; for it was not an easy matter to get together allies so many and so good.