Louis VII was born in 1120 in Paris,[citation needed] the second son of Louis VI of France and Adelaide of Maurienne. As a younger son, Louis VII had been raised to follow the ecclesiastical path. He unexpectedly became the heir to the throne of France after the accidental death of his older brother, Philip, in 1131. A well-learned and exceptionally devout man, Louis VII was better suited for life as a priest than as a monarch. In his youth, he spent much time in Saint-Denis, where he built a friendship with the Abbot Suger that served him well in his early years as king.

In the same year he was crowned King of France, Louis VII was married on 25 July 1137 to Eleanor, Duchess of Aquitaine, heiress of William X of Aquitaine. The pairing of the monkish Louis VII and the high-spirited Eleanor was doomed to failure; she once reportedly declared that she had thought to marry a king, only to find she'd married a monk. They had only two daughters, Marie and Alix. In the first part of Louis VII's reign he was vigorous and zealous of his prerogatives, but after his Crusade his piety limited his ability to become an effective statesman. His accession was marked by no disturbances, save the uprisings of the burgesses of Orléans and of Poitiers, who wished to organize communes. But soon he came into violent conflict with Pope Innocent II. The archbishopric of Bourges became vacant, and the King supported as candidate the chancellor Cadurc, against the Pope's nominee Pierre de la Chatre, swearing upon relics that so long as he lived Pierre should never enter Bourges. This brought the interdict upon the King's lands. Louis VII then became involved in a war with Theobald II of Champagne, by permitting Raoul I of Vermandois and seneschal of France, to repudiate his wife, Theobald II's niece, and to marry Petronilla of Aquitaine, sister of the queen of France. Champagne also sided with the Pope in the dispute over Bourges. The war lasted two years (1142–1144) and ended with the occupation of Champagne by the royal army. Louis VII was personally involved in the assault and burning of the town of Vitry-le-François. More than a thousand people who had sought refuge in the church died in the flames. Overcome with guilt, and humiliated by ecclesiastical contempt, Louis admitted defeat, removing his armies from Champagne and returning them to Theobald, accepting Pierre de la Chatre, and shunning Raoul and Petronilla. Desiring to atone for his sins, he then declared on Christmas Day 1145 at Bourges his intention of going on a crusade. Bernard of Clairvaux assured its popularity by his preaching at Vezelay (Easter 1146).