This is the third in the Aelfraed series from historical fiction author Griff Hosker. I haven't read the first two in the series, but was, unsurprisingly, attracted to the book by its Balkan content.
Our hero is one of two housecarls forced to flee England after the Norman contest. They first visit Denmark to seek support from the Danish king. Here they gain some companions and set off on a perilous journey down Russian rivers to Constantinople. They arrive after fighting off several Pecheneg attacks on their boat.
In Constantinople, they are rejected by the Viking dominated Varangian Guard, and join a unit of Saxon mercenaries. They fight against a Norman rebel in Anatolia and are quickly promoted by the Byzantine commander Alexios. After more than a few bouts with the complexity of Byzantine politics, Alexios becomes Emperor with their help. They end up commanding the Varangian Guard.
Their old enemies the Normans are never far away, and they are defeated at Dyrrachion (1081) by Robert Guiscard. However, they recover to push the Normans out of the Balkans in the final battle in which our hero... well I won't spoil the ending.
The author keeps to what we know of the history, largely the memoirs of Anna Comnena, albeit adding in these two redoubtable Saxons. There certainly were Saxons in the Varangian Guard of the period, if not in quite as significant roles!
This is really well written with all you would expect from the genre. Plenty of action, treachery and intrigue. Recommended.
And let's have some eye candy, with 28mm Varangian guardsmen from my Byzantine army of the period.