Carleond was the younger brother of Thierulf. The young Carleond, born in the lands of Lyonesse, was playing with his older brother Thierulf when they were set upon by a mighty lion, the last of its kind in all the lands of the Bretonni. Miraculously, the two children slew the beast, and skinned it so as to wear its fur. From then on, Carleond bore a rampant lion as his heraldry.
When the Grail Companions reached Couronne, it was Carleond who rallied the hosts of that land to his side, for their own king had been slain, and then he took part in the Eleventh and Twelfth Great Battles.
In the first fight, they faced the amassing armies of Orcs pushing toward L'Anguille. On the banks of the fast-flowing River Sannez battle was met, and the water ran black that day with the foul blood spilled. The Orcs turned their eyes from the great halo of light playing round the Companions, and were struck down into the mire as they turned to flee. It's said that never before had such a great toll of greenskins been slain upon a single day, nor ever since. So much tainted blood quenched the dry earth that it seems as marshland underfoot even to this very day.
On the last of the Twelve Great Battles, the plains of Couronne were invaded from the southwest by the Beastmen of the Forest of Arden and from the southeast by the greenskins of the Pale Sisters. The Companions made their prayers and arrayed themselves for this final battle, but disaster played its hand once more as, at their back, the fair city of Couronne was overrun by an unnatural tide of vermin. The Skaven killed the guard and erupted in great number from the gates to threaten the Companions from the rear. Surrounded on all sides by a number of foe beyond countenance, the Companions yet stood resolute and without fear; for the lords of each of the fourteen lands of the Bretonni now stood as one, the gathering complete, and their brotherhood and bonds of faith stood stronger than steel. They knew in their hearts the power of the Lady of the Lake flowed through them that day, and that none could stand against them. Each Companion performed such deeds as to fill the sagas until the end of time. The moons raced across the darkened sky, replaced by the burning orb of the sun, but to no respite. Only the Lady knows the number of weeks that saw battle, but against all odds, the mighty Companions emerged victorious. The piles of the dead were stacked like mountains, and searing pyres burnt the slain enemies for so long that night was turned to day for a season.
After the securing of all the lands of the Bretonni tribes, a great meeting took place in the home of Folgar of Artois. Here, the formal dukedoms were created, and the Bretonnian calendar was introduced - thus, year 979 of the Imperial Calendar is considered year 1 of the Bretonnian one. Each of the great lords of the Bretonni, the fourteen Grail Companions, including Gilles le Breton, were named Dukes. The Dukes swore oaths of allegiance, and Bretonnia was formed. In this meeting Carleond was appointed as the first Duke of Couronne.