The division of armed conflict into categories of terrorism, guerrilla warfare and conventional warfare is now less useful than perhaps it was in the past. Indeed definitions of the various classes of activity vary between commentators, between regions and across history. Robert Asprey's update of his 1975 book, War in the Shadows, encompasses a wide definition of the guerrilla. He covers those conflicts in which the organised forces of a state find themselves fighting against an enemy that uses unconventional -- in traditional military eyes -- tactics.

The scale of such an undertaking is reflected in the size of this work. The 94 chapters run from the troubles that Darius had with the Scythians in 512 bc through to the current difficulties with the Tamils in Sri Lanka. Keeping a sense of historical perspective across such a period and giving appropriate relative weight to different campaigns are just two of the problems in such a vast work. The more recent campaigns are better documented and unsurprisingly receive fuller treatment. Nevertheless, the detail of every operation is more than adequate.

At first sight such a massive work (which the author describes as "highly abridged") looks as though it would be of interest only as a reference book. Indeed, with 40 pages of double-column index, it makes a first-class database for the student of insurgency. Yet it is also written in a style that allows the reader to start at the beginning and remain fascinated until the end. It is a record across time and space of conflicts that have shaped the world today.

The first part is called "Lenin's Heritage", and takes us from Persia through Greece and Rome to conclude with the Russian Revolution. In the 13th century ad, we have arrived for our first of many calls in Vietnam. Asprey describes the Mongol attacks on the Gulf of Tonkin, and highlights the prescience of Marshal Tran Hung Dao, who trained a Vietnamese guerrilla force in 1284. Dao wrote: "The enemy must fight battles far from his home base for a long time . . . We must further weaken him by drawing him into protracted campaigns." On that occasion it took the Vietnamese freedom fighters three years to defeat Kublai Khan. Their techniques were to remain consistent and effective over the next 700 years.

ÁñÁ«ÊÓƵ

The second part, "Mao and Revolutionary Warfare", takes us from the Opium Wars to the Second World War. There are too many fascinating diversions to list, but my eye was inevitably drawn to a chapter that included a section on the use of air power for pacification. In a few pages we are taken through the development by the Royal Air Force of the use of air power for cost effective imperial policing between the wars. The strengths and weaknesses are all covered, as is the flavour of the inter-service rivalry of the day.

The third part -- some half of the book -- is titled "Ho . . . Ho. . . Ho Chi Minh", and takes us from the beginning of the Cold War through to Cambodia in 1993. However, most of this section reflects the author's preoccupation with Vietnam and in particular the involvement of the United States in the region. There is no doubt he feels very strongly about the need for America to learn the lessons of this war. As he says in his foreword: "The pages that follow emphasise the cost to any country when its civil and military leaders fail to consider yesterday while dealing with today." Despite the strength of his feelings, the descriptions remain factual, objective and well documented.

ÁñÁ«ÊÓƵ

The final section would make a perfectly satisfactory book on its own. Some 14 chapters cover the background to current insurgency problems, looking at South America, Northern Ireland, the Middle East, Southern Africa, the Kurdish diaspora, and South Asia. Having just returned from Namibia and Mozambique, I tested the book as one would a reference book before travelling to an unusual part of the world. In a few pages, the history of South West Africa/Namibia is covered right up to independence. Mozambique is similarly well described but its story finishes with the round of peace talks in July 1992: an indication of the difficulty of keeping every element of the book up to date.

Asprey explains that he wrote the first edition of War in the Shadows with intention of explaining the Vietnam War to American readers in the historical terms of guerrilla warfare. This edition has a dual aim. First, he wants to update the information on Vietnam in the light of the mass of evidence that has come to light since he wrote in the early 1970s. Second, he wants to report on the more important guerrilla wars of the post-Vietnam period. His foreword states there are some 18 countries hosting guerrilla wars, four countries with uneasy truces, and a further 14 with the potential for such conflicts. Curiously, this is distilled into the book's flyleaf as "thirteen countries currently experiencing guerrilla warfare". Whether this is a difference of timing, definition or accuracy between author and publisher is not clear and does not matter. The increasing incidence of conflict with non-conventional methods of fighting is apparent for all to see. The old certainties of conflicts between states using the conventions of war are giving way to ethnic, religious, tribal and warlord actions. Coupling these types of conflict with the modern weapons so widely available gives rise to a developing international problem.

To the general reader this book can be an aid to understanding the new developments on the international scene; to the British reader, Northern Ireland is likely to be of particular interest. To the military man, the book is an essential reader in counter-insurgency. To the policy-maker, it is an awful warning of the need for clear and sustained aims in any operation against guerrillas. At ?30, it must be the best value book in the field ever published.

Air Marshal Sir Timothy Garden is commandant of the Royal College of Defence Studies.

ÁñÁ«ÊÓƵ