A. J. Barker, a retired British military officer, is no shirker. He has written three excellent books in the past four years: The March of Delhi, Suez: The Seven-Day War, and Eritrea: 1941. As its subtitle indicates, The Bastard War is about a relatively unturned page of World War I: the campaign in Mesopotamia between 1914 and 1918. It is a tribute to Barker's scholarly industry that this exhaustive study precludes further investigation in this area in the immediate future. The story of the Mesopotamian campaign is one of political ineptitude and mismanagement, of muddled planning and military blunders. What makes Col. Barker's account of more than mere historical interest is his belief that the lessons to be learned from the campaign are as applicable today as they were fifty years ago. He reminds us that most of the problems of the modern world stem from the great upheavals of World War I. Since some of the more persistent trouble ""emanates from the region of the Persian Gulf--an area vital to Britain's economy, but where British influence has been steadily declining in recent years,"" the author rightly regards the Mesopotamian campaign as being of special significance. His thesis is consistently meaningful; his treatment of history objective; his presentation of background material judicious. Although its complexity makes it unsuitable for the average reader, war specialists will appreciate it.