He was married to Margaret de Clermont, sister of the Bishop of Tournai, and of the royal blood of France.
On the sea-banks, in the midst of the sand-hills, living by piracy, and by fishing, were colonies of Flemings. Furnes is the centre of this district. It was held by Clémence of Burgundy, the widow of Count Robert II., as her dowry. She had married one of her nieces to King Louis VI., another to William de Loo, Viscount of Ypres, son of Philip, her brother-in-law. Consequently there were several ambitious and powerful parties ready to lay claim to the County of Flanders, and wrest it from the hands of Charles.
The Flemings of the sea-coast rose, at the instigation of Clémence, and were secretly favoured by the King of France; whilst, at the same time, William de Loo asserted his claim.
The feudal nobles desired to profit by these circumstances, to increase their own power. One of them, Godfrey of Louvain, married the dowager countess, Clémence. The Counts of Hainault, Boulogne, S. Pol, and Hesdin, took arms. Clémence took Audenarde, the Count of S. Pol invaded West Flanders, but Charles fell suddenly on them with an army, subjugated De Loo, deprived S. Pol of his castle, and the countess of her dowry, dispersed the armed men of Hainault, Boulogne, and Coucy, and as Walter of Thérouanne says, "The land held its tongue before him." The king of France was the first to strike an alliance with him.
These successes excited the mistrust of the king of England and the emperor Henry V. The latter, under pretext of a war against the duke of Saxony, assembled an army in August 1124, crossed the Rhine, and marched towards Metz, threatening to destroy Rheims, where pope Callixtus II. had lately excommunicated him. In this imminent peril, all the vassals of the king rallied around Louis VI. "The noble Count of Flanders," says the abbot Suger, "brought with him ten thousand brave soldiers, and if there had been time, he would have brought thrice as many." In face of these preparations to resist his invasion the emperor withdrew to Utrecht. On his death, all eyes turned to Charles, and the imperial crown was offered him. He refused it, as he did also the crown of Jerusalem, offered him by the Christians in the Holy Land. He now devoted himself to the administration of his country with great zeal. He enacted wise laws, and laboured to make justice prevail in all the courts of judicature. Nevertheless a vague uneasiness prevailed amongst his subjects. The sea had overleaped the sand-hills, fires had broken out and consumed certain monasteries, and an eclipse of the sun gave prognostication of further evils. The winter of 1125 was of unparalleled severity; ice and snow prevailed till the end of March, and no sooner had the fields and woods begun to resume their verdant tints, than furious gales and a deluge of rain dissipated the hopes of the farmers. A dreadful famine ensued. "Some," says Gualbert, "perished before they could reach the towns and castles, where food was obtainable; others died in extending their hands for alms. In all our land the natural colour of the face had become exchanged for the pallor of death. Despair was general, for those who were not themselves in want sickened with grief at the sight of such miseries."