The siege of Damascus took place between 24 and 28 July 1148, during the Second Crusade. It ended in a crusader defeat and led to the disintegration of the crusade. The two main Christian forces that marched to the Holy Land in response to Pope Eugene III and Bernard of Clairvaux's call for the Second Crusade were led by Louis VII of France and Conrad III of Germany. Both faced disastrous marches across Anatolia in the months that followed, with most of their armies being destroyed. The original focus of the crusade was Edessa (Urfa), but in Jerusalem, the preferred target of King Baldwin III and the Knights Templar was Damascus. At the Council of Acre, magnates from France, Germany, and the Kingdom of Jerusalem decided to divert the crusade to Damascus.

The crusaders decided to attack Damascus from the west, where orchards of Ghouta would provide them with a constant food supply. Having arrived outside the walls of the city, they immediately put it to siege, using wood from the orchards. On 27 July, the crusaders decided to move to the plain on the eastern side of the city, which was less heavily fortified but had much less food and water. Afterwards, the local crusader lords refused to carry on with the siege, and the three kings had no choice but to abandon the city. The entire crusader army retreated back to Jerusalem by 28 July.

Louis VII (1120 – 18 September 1180), called the Younger or the Young (French: le Jeune), was King of the Franks from 1137 to 1180. He was the son and successor of King Louis VI (hence the epithet "the Young") and married Duchess Eleanor of Aquitaine, one of the wealthiest and most powerful women in western Europe. The marriage temporarily extended the Capetian lands to the Pyrenees, but was annulled in 1152 after no male heir was produced.

Immediately after the annulment of her marriage, Eleanor married Henry Plantagenet, Duke of Normandy and Count of Anjou, to whom she conveyed Aquitaine and produced five male heirs. When Henry became King of England in 1154 as Henry II, he ruled as king, duke or count over a large empire of kingdoms, duchies and counties that spanned from Scotland to the Pyrenees. Henry's efforts to preserve and expand on this patrimony for the Crown of England would mark the beginning of the long rivalry between France and England.

Louis VII's reign saw the founding of the University of Paris and the disastrous Second Crusade. Louis and his famous counselor Abbot Suger pushed for a greater centralization of the state and favoured the development of French Gothic architecture, notably the construction of Notre-Dame de Paris.

He died in 1180 and was succeeded by his son Philip II.