necessities of their armies.

To-day, the ability for aviation to carry increasing weight furnishes a new method for abundantly spreading poison gases with the aid of stronger and stronger bombs, and to reach armies, the centres of population in the rear, or to render regions uninhabitable.

Chemical warfare is therefore in a condition to produce more formidable results over more extended areas.

It is incontestable on the other hand that this growth will find an easy realisation in one country, Germany, addicted in times of peace, to wholesale manufacture of chemical products, which a simple modification in reactions can transform into war products.

This country, deprived, partially at least, of its former methods of fighting, and its numerous forces of specially trained soldiers, regularly organised and strongly armed, will be more drawn toward the new systems of attack-- that of chemical warfare.

Chemical warfare must therefore enter into our future provisions and preparations, if we do not wish to experience some terrible surprises.

The work of Major Lefebure gives an exact idea of the possibilities he finds to-day in Germany, and through them the dangers with which she threatens us. In this form it constitutes a warning; and information of the highest order, for the minds who remain anxious for the fate of their country confronted by the inefficience of the old fighting methods which the progress of industry out of date renders daily.

By sounding the alarm in both our countries, I find myself in company with my faithful friend Field Marshal Sir Henry Wilson. This is an old habit, contracted by both of us, many years ago, which we still maintain at the present time to insure for ourselves once again, peace in the future.

Together, we say, read this work of Major Lefebure. F. FOCH.

CONTENTS PAGE CHAPTER I-EXPLANATORY The Riddle of the Rhine-A Critical Point in Disarmament-Need for a Balanced View of Chemical Warfare-Some Preliminary Explanation--"Poison Gas" a Misleading Term-The French Physiological Classification-Asphyxiating Substances-Toxic Substances-Lachrymators-Vesicant or Blistering Compounds-Sneezing or Sternutatory Substances-The Tactical Classification-Persistent Substances-Non-persistent Substances-Penetrants-Special Gas Weapons and Appliances-Gas Shell. 17

CHAPTER II-THE GERMAN SURPRISE The First Cloud Gas Attack-The Element of Surprise -Lord Kitchener's Protest-German Preparations-- Research-Production-Field Preparations-German Opinion of Results-Germany Prompted by Production Monopoly-Standard Uses for Gas-Gas Shell-Further German Cloud Attacks-Hill 60-Origin of German Gas Shell-Early German Gas Shell-A Successful Experiment-Lachrymators at Loos, 1915-The Flammenwerfer-German Phosgene Clouds-Gas and the Eastern Theatre-Conclusion. 31

CHAPTER III-THE ALLIED REACTION The Need of Retaliation-First Signs-The Loos Attack, September, 1915-The Somme Battle, 1916--Reasons for British Cloud Gas Success-Our Casualties-Exhausting Preparations for Cloud Attack-The Livens Projector-British Gas Shell-German Gas Shell Development, 1916-Main Features of the Period. 48

CHAPTER IV-INTENSIVE CHEMICAL WARFARE The Mustard Gas Surprise-Blue Cross-German Emphasis on Gas Shell-The German Projector-German Projector Improvements-Dyes in Gas Shell--German Flame Projectors-Their Origin-Further Flame Development-The 1918 Offensive-Ludendorff's Testimony-Preparations for Assault-Gas Defensive Flank at Armentieres-Fixed Gas Barrage at Kemmel-Percentage of Chemical Shell-Gas Re-Contents

PAGE treat Tactics-General Hartley's Analysis-Percentage of German Gas Shell in Enemy Dumps-Forced Exhaustion of Stocks-Yperite, French Mustard Gas-Effect on German Gas Discipline-Allied Gas Statistics-Critical Importance of Rapid German Production. 66

CHAPTER V-CHEMICAL WARFARE ORGANISATIONS German Research-Leverkusen-Hochst-Ludwigshaven-Early Formulation of Policy-Movements