Gaius distinguishes himself as an artilleryman decorated by Trajan. The Tigris River is crossed. Babylon, Seleucia, and the Parthian Capital Ctesiphon fall, but hostile climate, revolts, and health problems cause Trajan's withdrawal and a stroke his death as the Second Traiana Fortis and Gaius march to Caesarea Maritima.
While Gaius polices complaints in Judea , new Imperator Hadrian executes four men of consular rank who served Trajan. Gaius replaces crooked overseers on estates leased in Judea as danger of revolt subsides but is alarmed to find swords made there under contract for the Roman Army on many estates. His energy and literacy gain him the rank of centurion.
Legate Publius Junius and Gaius are recalled to Rome. Publius Junius is retired, and coldly told by Imperator Hadrian, "You have escaped."
Gaius, after a few days with his family, must sail to Britannia to serve the Twentieth Valeria Victrix Legion as centurion and liaison to the British auxiliaries whose language he speaks as they combat the warlike Caledonians who have inflicted heavy casualties and soon destroy the Ninth Hispanic Legion.
Backed by the Sixth Victrix and Second Augusta Legions, the Twentieth with excellent British auxiliaries defeats the Caledonians until desolation makes peace.
Gaius is Master of Arms of the Twentieth, whose Legate- Governor Nepos blames the greedy Brigate King Roscius for the Ninth's fate. Heroic Primus Pilum Sentius selects Gaius to replace him as Primus Pilum. Governor Nepos accepts this.
Gaius is haunted by the poverty awaiting maimed legionaries and tries to think of a just remedy for their misery.
Hadrian, trying to be a good Imperator trains the legions living as a common soldier drilling them in every tactic with every arm. He comes to the Twentieth.
Gaius, who has quit the Master of Arms title tries to avoid him, but is revealed by the new master. Resembling his father Marcus Furius in looks and strength, Gaius does an uncanny trick with a coin and his sword both of which Hadrian knows, calling on the Imperator to give justice and mercy to the maimed men of the legions by building a wall across Britannia that they can defend while teaching enlisted British auxiliarlies.
Hadrian likes the idea. He will be the soldiers' friend. He gives Gaius permission to marry Sephrona, a retired centurion's daughter at Deva so long as she stays outside of the camp and away from campaigns.
Hadrian exiles King Roscius of the Brigantes and begins the Wall in the east planning a fort every Roman mile with two watchtowers in between, each big enough to hold a decury. Every legion in Britannia works on the Wall.
After Governor Nepos' departure, Legate Veres sends a vexillation of the Twentieth under Gaius' direction to work on the Wall in the west. This being neither fort or campaign, Sephrona and son, Gaius Heraclius, come along with optio Norbanus in kindly Legate Veres' carrucca dormitoria. For years work progresses until under Governor Germanus Hadrian's Wall is completed- a huge fort for the maimed legionaries to draw full pay in whiile training British auxiliaries.
Gaius and family are recalled to Rome where he is made Palace Master of Arms to the Praetorian Guard and to Hadrian's cadets including the stunningly perfect and intelligent Antinous. Hadrian leaves for Africa. Meanwhile, Gaius and Prefect Turbo discover a plot toward a colossal revolt in Judea under Simon bar Kokhba. Gaius leads a legion of British auxiliaries to the conclusion of the ghastly eastern conflict and retirement.