After this series is once worked through with the men, other problems on different ground are taken. It takes considerable work of this kind to make the men proficient in the principles of patrolling. As soon as they are deemed proficient they should be taken out for tactical walks in patrol problems on the ground and there given problems to solve, the instructor acting as umpire. This is all work that can be done in most posts in the winter season by taking advantage of the most favorable weather for the outdoor part. The instruction in the principles of patrol leading can be given to better advantage on the relief map or sand table than on the ground but the latter training can not be dispensed with, some of it must be given. Later on there should be much opportunity for further practice in the course of the combat exercises. [Sidenote: Other kinds of patrolling] The work of the expeditionary patrol should be taught in the same manner. The work of the visiting and connecting patrols can be taught during the exercises in advance guard and outposts. They require very little effort. The company as a whole should be frequently exercised as a strong patrol. There is one form of patrol, often very strong, that is of great importance and yet its proper training is frequently neglected—the combat patrol. These patrols are always thrown out when a command deploys for action and upon their proper conduct much depends. Their mission is always to prevent the firing line from being unexpectedly fired into from the flank and they fulfill this mission according to the situation, either by securing the flank by themselves holding off the enemy, or by observing and giving timely warning so that the support or reserves can be disposed to meet the enemy and thus ward off the attack. It must be thoroughly impressed on all what the mission of the combat patrol leader really means and that any position or formation of such a patrol, that allows the firing line to be so attacked is all wrong. [Sidenote: The combat patrol] The following must be thoroughly taught: 1. That when the patrol is so situated that it can see no more than the men on that flank of the firing line it is serving no valuable purpose. 2. That in practically all cases where it is not in advance of the firing line it will not gain the necessary information in time to be of any value. 3. That the enemy must not get within effective rifle range of the flank of the line. The strength of the combat patrol must depend on whether it is merely to observe or to offer real resistance and its conduct must be governed accordingly. It is believed that the principles governing this work can be best taught, after a talk in the school, by a form of tactical walk, where the instructor can devote himself to the handling of this patrol; later on it is, of course, practiced in all battle exercises. [Sidenote: Combat patrol tactical walk]