Eu is located near the coast in the eastern part of the department, near the border with Picardy.
Its inhabitants are known in French as the Eudois.
In 1050, William, Duke of Normandy, the future William the Conqueror and king of England, married Matilda, the daughter of the Count of Flanders, at the chapel of the castle in Eu. The chapel is the only part of this castle which still stands today.
In 1180, Laurence O'Toole, the archbishop of Dublin and papal legate, fell ill at Eu on his way to meet King Henry II of England. He died there. He was beatified in 1186 and canonised in 1225 as St Laurence, becoming the patron saint of the town. The collegiate church was named for the Virgin Mary and for him, Notre-Dame et Saint-Laurent, and still holds some of his preserved relics. In the 12th century, King Richard I of England, who was also Duke of Normandy, built the city walls.
The county remained an independent fief of the French crown until 1472, when it was inherited by John, Count of Nevers. In 1477 it was incorporated into the Burgundian territories of Charles the Bold. However, later that year Charles was killed in battle; King Louis XI of France took the opportunity to seize Charles' French fiefs, including Eu, and incorporated them in the French royal domain.
The British Queen Victoria visited Eu on two occasions as guest of Louis-Philippe. The first time in 1843 was to cement an early form of the Entente Cordiale between Britain and France. It was the first time monarchs of the two countries had met since King Henry VIII of England met with King Francis I of France on the Field of the Cloth of Gold in 1520.
The Croix de Guerre was awarded to the town in 1944.