After being owned by the Counts of Flanders, Lillers, which had been fortified against the Normans was given as a dowry in 1179 to King Philip II Augustus of France.

In 1340, King Edward III of England claimed the throne of France and started the Hundred Years War, marked by two famous battles, that of Crécy 1346 and that of Battle of Agincourt, 1415, where Robert Wavrin, Lord of Lillers, met his death.

In 1542, during the war against Charles V, Holy Roman Emperor, French troops burned Lillers.

After a period of peace, the Thirty Years' War caused devastation in the region.

The Treaty of Utrecht ended the war in 1713, when Lillers found itself a part of France.