The Art of War by active 6th century B.C. Sunzi

28. Now a soldier’s spirit is keenest in the morning;

[Always provided, I suppose, that he has had breakfast. At the battle of the Trebia, the Romans were foolishly allowed to fight fasting, whereas Hannibal’s men had breakfasted at their leisure. See Livy, XXI, liv. 8, lv. 1 and 8.] by noonday it has begun to flag; and in the evening, his mind is bent only on returning to camp.