History of the Peloponnesian War

The cause was not so much lack of men as lack of money. For it was a want of supplies that caused them to take out a comparatively small force, only so large as could be expected to live on the country while at war. And when they arrived and had prevailed in battle—as evidently they did, for otherwise they could not have built the defence around their camp—even then they seem not to have used their whole force, but to have resorted to farming in the Chersonese and to pillaging, through lack of supplies. Wherefore, since they were scattered, the Trojans found it easier to hold the field against them during those ten years, being a match for those who from time to time were left in camp.

But if they had taken with them an abundant supply of food, and, in a body, without resorting to foraging and agriculture, had carried on the war continuously, they would easily have prevailed in battle and taken the city, since even with their forces not united, but with only such part as was from time to time on the spot, they yet held out; whereas, if they could have sat down and laid siege to Troy, they would have taken it in less time and with less trouble. But because of lack of money not only were the undertakings before the Trojan war insignificant, but even this expedition itself, though far more noteworthy than any before, is shown by the facts to have been inferior to its fame and to the tradition about it that now, through the influence of the poets, obtains.