Combat took place between masses in more or less deep formation commanded and supervised by leaders with a definite mission. The combat between masses was a series of individual conflicts, juxtaposed, with the front rank man alone fighting. If he fell, if he was wounded or worn out, he was replaced by the man of the second rank who had watched and guarded his flanks. This procedure continued up to the last rank. Man is always physically and morally fatigued in a hand-to-hand tournament where he employs all his energy. These contests generally lasted but a short time. With like morale, the least fatigued always won. During this engagement of the first two ranks, the one fighting, the other watching close at hand, the men of the rear ranks waited inactive at two paces distance for their turn in the combat, which would come only when their predecessors were killed, wounded or exhausted. They were impressed by the violent fluctuations of the struggle of the first rank. They heard the clashes of the blows and distinguished, perhaps, those that sank into the flesh. They saw the wounded, the exhausted crawl through the intervals to go to the rear. Passive spectators of danger, they were forced to await its terrible approach. These men were subjected to the poignant emotions of combat without being supported by the animation of the struggle. They were thus placed under the moral pressure of the greatest of anxieties. Often they could not stand it until their turn came; they gave way. The best tactics, the best dispositions were those that made easiest a succession of efforts by assuring the relief by ranks of units in action, actually engaging only the necessary units and keeping the rest as a support or reserve outside of the immediate sphere of moral tension. The superiority of the Romans lay in such tactics and in the terrible discipline which prepared and assured the execution. By their resistance against fatigue which rude and continual tasks gave them and by the renewal of combatants in combat, they secured greater continuity of effort than any others. [4] The Gauls did not reason. Seeing only the inflexible line, they bound themselves together, thus rendering relief impracticable. They believed, as did the Greeks, in the power of the mass and impulse of deep files, and did not understand that deep files were powerless to push the first ranks forward as they recoiled in the face of death. It is a strange error to believe that the last ranks will go to meet that which made the first ones fall back. On the contrary, the contagion of recoil is so strong that the stopping of the head means the falling back of the rear! The Greeks, also, certainly had reserves and supports in the second half of their dense ranks. But the idea of mass dominated. They placed these supports and reserves too near, forgetting the essential, man.