CHAPTER XI. =OBSTACLES=--Object--Necessity for 1173-1193 Obstacles--Location--Abatis--Palisades--Fraises-- Cheveaux de Frise--Obstacles against Cavalry--Wire Entanglements--Time and Materials--Wire Fence--Military Pits or Trous de Loup--Miscellaneous Barricades-- Inundations--Obstacles in Front of Outguards--Lessons from the European War--Wire Cheveaux de Frise--Guarding Obstacles--Listening Posts--Automatic Alarms--Search Lights. CHAPTER XII. =TRENCH AND MINE WARFARE=--Asphyxiating 1194-1211 Gases--Protection against Gases--Liquid Fire-- Grenades--Bombs--Aerial Mines--Winged Torpedoes--Bombs from Air-Craft--Protection against Hand Grenades-- Tanks--Helmets--Masks--Periscopes--Sniperscopes--Aids to Firing--Mining--Countermining. CHAPTER XIII. =MARCHES=--Marching Principal Occupation 1212-1229 of Troops in Campaign-Physical Training Hardening New Troops--Long Marches Not to Be Made with Untrained Troops--A Successful March--Preparation--Starting-- Conduct of March--Rate--Marching Capacity--Halts-- Crossing Bridges and Fords--Straggling and Elongation of Column--Forced Marches--Night Marches--No Compliments Paid on March--Protection on March--Fitting of Shoes and Care of Feet. CHAPTER XIV. =CAMPS=--Selection of Camp Sites-- 1230-1240 Desirable Camp Sites--Undesirable Camp Sites--Form and Dimensions of Camps--Making Camp--Retreat in Camp-- Parade Ground--Windstorms--Making Tent Poles and Pegs Fast in Loose Soil--Trees. CHAPTER XV. =CAMP SANITATION=--Definition--Camp 1241-1255 Expedients--Latrines--Urinal Tubs--Kitchens--Kitchen Pits--Incinerators--Drainage--Avoiding Old Camp Sites-- Changing Camp Sites--Bunks--Wood--Water--Rules of Sanitation--Your Camp, Your Home. CHAPTER XVI. =INDIVIDUAL COOKING=--Making Fire-- 1256-1275 Recipes--Meats--Vegetables--Drinks--Hot Breads-- Emergency Ration. CHAPTER XVII. =CARE AND PRESERVATION OF CLOTHING AND 1276-1320 EQUIPMENT=--Clothing--Pressing--Removing Stains-- Shoes--Cloth Equipment--Washing--Shelter Tent--Mess Outfit--Leather Equipment--Points to Be Remembered. CHAPTER XVIII. =CARE AND DESCRIPTION OF THE RIFLE= 1321-1343 --Importance--Care of Bore--How to Remove Fouling--Care of Mechanism and Various Parts--How to Apply Oil--Army Regulation Paragraphs About Rifle--Nomenclature of Rifle. PART IV RIFLE TRAINING AND INSTRUCTION