Emperor - Colin Thubron

The Emperor Constantine crosses the Alps at the head of a great army from the Rhineland in AD 312, and marches south to take Rome from the tyrant Maxentius. As he lays siege to the city of Verona, Constantine waits for the arrival of his wife, Fausta - his enemy's sister - whose cool detachment torments him. Emperor is a superbly imaginative reconstruction of the dramatic weeks leading up to Constantine's triumph in Rome. Written in the form of extracts from his own journal and letters from his empress, her frivolous female companion, his cynical secretary and a Christian bishop who is travelling with the army, the novel records a train of events which will change the world.
Constantine is plagued by spiritual doubts, tortured by his wife's coldness, but he defies the omens to win a great victory at Verona and to lead his army south. On the road to Rome, the conqueror becomes the conquered as a blinding vision strikes him from his horse in an astonishing conversion to Christianity. Emperor summons up the Roman world of two thousand years ago, the everyday life of soldiers on campaign and the intrigues at court. But it is also the many-faceted story of a man's loss of faith in God and in human love, told with uncanny brilliance.