PARRY THE OPPONENT'S STRIKES
The more your opponent strikes you, the weaker you and your resolve will become, and the less able you will be to strike him.
You must try to anticipate where your opponent will strike; you must consider your vital points, the opponent, and the context. Caesar’s creating a fourth line of battle at Pharsalus to meet Pompey’s cavalry, which were far more numerous than his own, is a perfect instance of parrying a strike.
Your opponent seeks always to surprise you, you not to be surprised. “One must always assume,” said Napoleon, “that the enemy has made movements during the night, in order to attack at daybreak.”
The Nervii had been told by Gauls within Caesar’s camp that, in the Roman order of march, each legion would be followed by its baggage train. They resolved on attacking the Romans on seeing the first baggage train; they would thus be able to destroy each legion as it came up. Whenever near an enemy, however, Caesar would mass his legions; as they marched toward the Sambre River, the Romans observed the following order: Caesar, the cavalry, and light infantry in front, followed by six legions; then, the baggage train followed by two. The Romans destroyed the Nervii force.
Richelieu created a superb intelligence service so that he might know what his opponents were plotting against him.
You can parry a strike by striking. When King Juba of Numidia marched against him, Caesar had one of his legates attack Juba’s kingdom, forcing Juba to return as quickly as possible.
You can also deflect a strike by deceiving. On learning that the Romans would fall upon his army as it marched through a valley the following day, that night Hannibal had twigs tied to the horns of oxen, the twigs lit, and the oxen sent off by another path. Thinking the lights those of the Carthaginian army, the Romans set out in pursuit. The following morning, the Carthaginians marched through the valley untouched.