Being only 14 at the start of his reign, Queen Mother Judith, his grandmother, saw herself as regent for the third time. The Duchy of Munster was once more restless, this time under the rule of Art, Imag's young son. Art's rebellion was quite a bit more dangerous than Imag's, however, for he had inherited both Connacht and Munster. This put him in charge of more Irish land than the royal crown and, subsequently, quite a bit more manpower than his mother ever had at her disposal.
Seeing another young king on the Breton throne, the duke rebelled two weeks after Briant's coronation. The Duke of Ulster declared independence the next week, sparking a full Irish rebellion against Briant's rule.
Judith resolved to crush the rebellion with as much force as possible, ordering the full might of Breton arms into the fray. Over 10000 troops were raised on the mainland and sent to reinforce the small but loyal Duke of Leinster's army. 8000 troops under Briant's banner, led by the Duke of Leinster, met Duke Art's forces on the plains outside Wexford on January 30th, 1185. The battle raged all day and into the next, ending the the Munster forces in full retreat. Loyalist forces harassed Art for a week, picking at his forces until he had practically no armies in the field.
Still, the war dragged on. The rebel garrisons were stout-hearted and well stocked with provisions to hold out for years. Worse, the situation forced the Breton war council to choose between Munster and Ulster; there simply weren't enough soldiers or supplies to handle both. It was decided to let Ulster take a back seat for as long as was needed to pacify the south of Ireland, even if that meant letting Ulster break free. Brittany settled in for a long war.
Briant reached the age of majority in 1186. He proved to be amazingly deft with money, able to wring every penny out of the books without raising taxes. Over the years, this seemingly preternatural talent with the kingdom's finances helped to offset the costs of the nearly constant warfare of his reign.
The same year, Briant married Barbara Salian, younger sister of the Holy Roman Emperor, Ernelrich I. She was a Lollard but converted during her wedding ceremony as a condition of the marriage. She was a good match for Briant, studious and kind. She was quite beloved by her subjects, referred to as Barbara Le Bon.
In 1188, the Wales and her ally, Normandy, joined in the Irish war. The kingdom laid claim to the central county of Breifne, held by Munster. The Welsh forces invaded with a massive force, scuttling any plans for a quick, simple dismantling of the Munster garrisons. A vicious three way conflict settled over the island, with no end in sight.
The following year, Briant and Barbara's first child, a girl named Marguerite, was born. She was healthy and fair, proving quite popular at court as she grew up.
In early 1191, the first step in the cessation of the interminable seven year long Irish rebellions occurred with the granted independence of the Duchy of Ulster. Briant, in his letters, resolves to his council that he will retake the northern Irish duchy once the truce between they and Brittany ended, but for the time being, Ulster was free of Breton rule.
By the fall of 1191, Brittany had decisively beaten back the Welsh and Norman armies, allowing proper sieges of the holdings of Munster to be set up. Duke Art surrendered that year and was locked away. A compromise was reached whereby the title to the Duchy of Connacht would pass to his family, while the Duchy of Munster was given to Briant's childhood friend, Jourdain Taillefer.
Briant's religion then called him to war in the Levant. Pope Honorius II had declared the Third Crusade in 1188. With the political situation in Ireland, Briant could not go on crusade. Once the wars were over, Briant mustered his forces for the long voyage over the Mediterranean. Judith and the Barbara ran things together in his absence.
Briant's landing was hailed by the weary Christian forces. The Crusade had been wearing on for three years by 1191 and the situation in the Holy Land was eerily similar to that in Ireland. Several Muslim caliphates had taken advantage of the Crusade to launch their own battles against the massive Shia Caliphate which was in control of Jerusalem. Not merely a three way war, such as he had concluded in Ireland, but a seven way battle for the heart of the Levant faced Briant when he set foot on the Levantine coast.
Success came quickly and easily for the Bretons at first. For three years, Briant and his forces took city after city. Gradually, however, the Bretons were driven back into the sea, far as they were from reinforcements and supplies. Briant returned in 1195 to a hero's acclaim, though his gains were short-lived. After the savage and ugly fighting in Ireland, during which the nakedness of the ambition of the men fighting and the ugliness of war was apparent to all, the prospect of fighting for the Holy Land, even if it was ultimately unsuccessful, must have seemed entirely noble and worthwhile.
In 1194, Barbara gave birth to a son, Maurice. The child was born with crippling mental retardation. That this was present in the royal heir was devastating news. Judith, still Brittany's spymaster, resolved to quietly rectify what she saw as a dangerous situation. While not revealed during her lifetime, the Queen Mother had the infant smothered in his sleep. He was only three months old. Queen Barbara was devastated.
1195 saw the birth of a second son, Ogier. Again, the boy suffered from a malaise of the brain. While not as crippling as that of his dead brother, he was obviously slow. With Briant returned from crusading, there would be no second child murder in Rennes Castle. The heir would live.
As fate would have it, the dim-witted scion of the de Rennes family would be named king far too soon even for a fully capable person. Briant II died while holding court on Pentecost at the age of 26, in 1196. Modern experts, having scoured the contemporary records, have determined that there was no foul play involved; it seems as though he died of what sounds like a pulmonary embolism.
At barely five months of age, Ogier was king and Judith found herself Regent of Brittany for an astounding fourth time.