In my opinion, this book is the best of the "Fontana History of the Ancient World" series. Professor Cameron succeeds in presenting a concise overview of the later Roman Empire. Her style is scholarly, but not pedantic. She does what a responsible historian should do, and encourages her readers to consult the primary sources on the subject. Her study offers a wide panorama of political, military, social, economic, religious, and cultural issues. She also makes extensive use of archaeological, epigraphical, and numismatic evidence. The maps and photographs provided are a bit disappointing, but the bibliography is first-rate.
The events of this era were decisive and remain controversial. The destruction of the classical world, and its replacement by a more authoritarian feudal society, was a brutal process. It meant destroying an entire civilization. People enjoyed a high degree of social mobility in the classical world; but by the time of the Middle Ages, most of the population were slaves. Some historians, such as Gibbon, regard the advent of Christianity as the decisive factor in this upheaval. Cameron adopts a more neutral approach, and prefers to observe this transformation without passing judgement on it. She does not necessarily view this period as one of "decline", because many Roman institutions subsisted well into the Middle Ages.
Cameron's underlying theme is the political re-organization of the Empire, and the importance of the early Church in this undertaking. The new order was symbolized by the development of Constantinople as the new imperial capital, accompanied by a frenzy of church-building. Gymnasiums and public baths progressively disappeared as institutions of social learning. Christian beliefs and values - encapsulated by St. Augustine - supplanted classical education. Clergymen now competed with nobles for power, and barbarians were amalgamated into the military (Constantine abolished the Praetorian Guard). However, Cameron points out that reform was by no means a foregone conclusion. She devotes an entire chapter to Julian (the last pagan emperor) and pagan opposition.
Surveying the Roman economy, Cameron explores the role of slavery and large landed estates. The silver coinage was debased to pay for wars, yet the Church grew fabulously wealthy. Buying off barbarian invaders became an established practice, resulting in heavy taxation. In cultural matters, Cameron argues that Christianity recycled many pagan beliefs and customs, giving birth to a myriad of sects and breakaway groups (especially in the East).
Overall, this is a very accessible work that constitutes an excellent introduction to the period. For those who wish to delve more into this era, I would recommend reading the relevant primary sources (Ammianus Marcellinus, Procopius, St. Augustine, St. Jerome, etc.). Good modern studies include Gibbon's "Decline & Fall", J.B. Bury's "History of the Later Roman Empire", or Peter Brown's "The World of Late Antiquity".