In 886, bishop Gauzlin of Paris asked count Erkenger of Boulogne to solicit German help against the Viking raids.

Count Renaud of Boulogne joined the imperial side at the Battle of Bouvines in 1214, and he was defeated by Philip II of France.

Having become Afonso III of Portugal in 1248 and renounced his title of Count of Boulogne, Alfonse divorced her in 1253 due to her barrenness in favour of Beatrice of Castile.

By his marriage to Jeanne of Bourbon-Vendôme, he left two daughters: The representatives of the County joined in the Netherlands the Estates General of 1464 in Bruges.

At the death of Charles the Bold the King of France claimed the end of the dependency of Boulogne from the County of Artois, causing new struggles against the Habsburg.

The treaty of Senlis closed the problem: France lost Artois to the Empire, while the Habsburg renounced to Boulogne.