History of the Peloponnesian War

We have now, therefore, been forced by the numbers of those opposed to us to discontinue the work of circumvallation, and to remain inactive; being unable to make use even of all the force we have, since a large portion of our heavy infantry is absorbed in the defence of our lines. Meanwhile the enemy have carried a single wall past our lines, thus making it impossible for us to invest them in future, until this cross wall be attacked by a strong force and captured.