In this street there are six empty wagons and in the houses in the street there is to be found furniture of all descriptions, as well as ropes, harness, and stables, with some horses in them. You are anxious to place a barricade across the street _A H_ at _D_, so as to enable you to use the crossing at _D_. How should you set about making this barricade? (_c_) There is a house at _H_ looking right down the street _A H_. Whereabouts in this house should you put your Lewis gun, and why? _Solutions._ (_a_) On the western side, because your men, shooting out of the windows in a northerly direction, would then fire from their right shoulders without exposing their bodies. (_b_) Fill the wagons with rubble from the houses which have been knocked down. Fasten sacking or sheets on to the wagon, so as to give cover from view between the body of the wagon and the ground. Throw a string attached to a brick across the street. By means of this, pull over a rope and attach the wagons to this rope, and thus pull them into the position you require. (_c_) At the back of a room in the house, where you can see but cannot be seen, firing through the window. If you choose a window near the top of the house and put the Lewis gun on a table some distance back in the room, you will probably be able to fire over the barricade which you are thinking of constructing at _D_. I have put you three definite and very simple questions with regard to street-fighting, for it may often happen that correct action on the spur of the moment when a village is first entered may result in ground being easily gained which would otherwise entail heavy fighting and serious loss to capture. Street-fighting is a very big subject, and as a rule it gradually develops into underground warfare. Villages entered during a battle often have snipers in the top stories or on the roofs of the houses, and these are places in which you may also place a few good shots with great advantage. This is an illustration of the advisability of doing to the enemy what you do not like his doing to you. I will send you another problem next week. Your affectionate father, “X. Y. Z.” LETTER IV [Illustration] _December 22, 1917._ MY DEAR DICK,-- You have told me that you have once or twice temporarily commanded a company and have asked me whether I think there is any advantage in a young and active company commander being mounted. In another part of your letter you ask whether I think a defensive position should be taken up on a forward or on a reverse slope.