The book brought to the attention of the reader is dedicated to one of the most dramatic periods of the existence of the Roman Empire, which began with the turbulent reign of Constantine the Great and ended with the battle of Adrianople, which cost the life of Emperor Valens and the best part of his army. Already contemporaries wondered what caused such a terrible catastrophe. Many modern researchers believe that the outcome of the battle was predetermined by some technical and tactical innovations resorted to by the Goths and their allies... It would be more correct, however, to ask the question not why the Roman army was defeated in one battle, but why this battle had such an impact disastrous consequences for the entire Roman world and essentially put an end to the centuries-old history of Roman military dominance. The answer to this question can only be given by tracing the chain of events that preceded the Battle of Adrianople...