Prince Hoel, so far from acquiescing in his father's will, immediately levied an army to maintain his rights, and a civil war ensued between the brother and sister, which lasted for twelve or fourteen years. Bertha, whose reputation was not much fairer than that of her mother Matilda, was succeeded by her son Conan IV.; he was young, and of a feeble, vacillating temper, and after struggling for a few years against the increasing power of his uncle Hoel, and his own rebellious barons, he called in the aid of that politic and ambitious monarch, Henry II. of England. This fatal step decided the fate of his crown and his posterity; from the moment the English set foot in Bretagne, that miserable country became a scene of horrors and crimes--oppression and perfidy on the one hand, unavailing struggles on the other. Ten years of civil discord ensued, during which the greatest part of Bretagne was desolated, and nearly a third of the population carried off by famine and pestilence. In the end, Conan was secured in the possession of his throne by the assistance of the English king, who, equally subtle and ambitious, contrived in the course of this warfare to strip Conan of most of his provinces by successive treaties; alienate the Breton nobles from their lawful sovereign, and at length render the Duke himself the mere vassal of his power. In the midst of these scenes of turbulence and bloodshed was Constance born, in the year 1164. The English king consummated his perfidious scheme of policy, by seizing on the person of the infant princess, before she was three years old, as a hostage for her father. Afterwards, by contracting her in marriage to his third son, Geoffrey Plantagenet, he ensured, as he thought, the possession of the duchy of Bretagne to his own posterity.