The role of the English mercenaries in the Byzantine army has long been under dispute. A. A. Vasiliev, writing in 1937, gave a very full summary of what was known at that time, and tended to stress their importance to Byzantium in the later eleventh century. However, his article came under brief but formidable attack from the German scholar, F. Dölger, who published a review of Vasiliev's work in 1938. A year later, Dölger's arguments were repeated and amplified by S. Blöndal. Since then, the dispute has hung fire, and a recent historian of the Byzantine army, A. Hohlweg, was justified when, in 1965, he wrote of the problem of the role of the English as umstritten — disputed. What follows is an attempt to reassess the problem and my conclusion is akin to Vasiliev's: there was a significant migration of Anglo-Saxons to the Byzantine Empire around 1080, and in the early years of Alexius Comnenus‘ reign. Further, there is evidence of diplomatic contact between the Empire and the rulers of England, and groups of Anglo-Saxons may have continued to migrate eastward later than has previously been thought. But the value of the English was probably greatest in the early years of Alexius Comnenus’ reign, and may even be compared with that of the Russians who had come to the rescue of the emperor Basil II nearly a hundred years earlier, in about 988.