=Troops Detailed for the Counterattack.= The company, or companies, held as reserve of the center of resistance, are divided into half-companies or platoons under the command of a single leader. Each one of these detachments is assigned to a support point and is put at the disposal of the captain commanding the same, to counterattack on his first line if captured by the enemy. In order to secure the proper liaison between these two units, the counterattack troops send a messenger to the command post of the support point which they are assigned to. When the hostile attack is executed and counterattack troops are needed, the captain sends this messenger back to call them up. =Routes or Directions for Counterattacks.= Each detachment of counterattack troops has a fixed route for its attack laid down in the plan of defense. Usually a boyau that it employs or along which it travels, fixes the direction. For this reason, in the interior of the position gaps are left in the barbed wire entanglements to permit the passage of these troops in the counterattack. Portable chevaux-de-frise are employed to fill up these gaps when necessary. =Form of the Counterattack.= The counterattack may be executed as a frontal or a flank attack. Frontal counterattacks are, perhaps, not as effective as the latter, but they are more easily executed, especially in the case where exact knowledge of the situation in the line in front is not known. This is the form of advance employed in the support point where the reinforcing platoons, starting forward to strengthen the line and finding it captured, change their tactics by leaping over the top and charging the line with grenades and bayonets. [Illustration: EXAMPLE OF A COUNTER ATTACK EXECUTED BY TWO PLATOONS OF CENTER OF RESISTANCE SUPPORT] A counterattack to the flank usually involves a little maneuvering. The most successful of these attacks are those executed in two detachments— for example, a party of grenadiers may attack the enemy occupying a part of the area either on one or both flanks. Its approach is usually through a trench or boyau. A second party of riflemen, at the same time, will make a frontal attack on the enemy over the top with bayonets. To completely surround the enemy, an artillery barrage is sometimes established to cut him off from the rear. The battalion commander works out the plan of counterattack down to the most minute detail. But when the hostile attack is carried out, he is no longer the master of it. All the foreseen movements start at the proper time and are carried out in their workings like a piece of mechanism. The time of the start of the counterattack is in reality given by the enemy himself.