Sextus Iulius Frontinus is best known as author of the military handbook Strategems but, in addition to writing this and other works (now lost), he also had a varied and surprisingly influential career in military and civil posts around the Roman Empire. Frontinus loyally served at least six emperors, often acting as a trusted counsellor, and even deputized for Trajan while he was busy in Germany and elsewhere. He was possibly the longest-serving governor of Britain (five years), where he completed the subjugation of Wales and established the frontier in northern England at the Ribble-Tees line. He founded several legionary fortresses, including those that later became the towns of York, Chester and Caerleon. He also served on the Rhine, in Spain and Asia and in the civil sphere reformed the water supply of Rome. John Grainger has written the first full biography of Frontinus. Reconstructing his life to the fullest extent permitted by the sources, he favourably re-evaluates his importance, particularly in Britain (at the expense of the better-known Agricola. Froninus' career, the author concludes, is one of the most varied and significant of any that can be reconsructed for any Roman who did not become Emperor.