Beaitais (anc. Casaromagw), a city of France, capital of the department of Oise, situated on the Therain, 40 m. N. by W. of Paris; pop. in 1866, 15,307. When the Romans invaded Gaul, it was the chief town of the Bello-vaci. It became early the seat of a bishopric, the holder of which was one of the 12 peers of France under the Capetian kings. The English made an unsuccessful assault on the city in 1433, but they held the surrounding country, and it was Pierre Cauchon, bishop of Beau-vais, who pronounced the sentence of death upon Joan of Arc. In 1472 the city, being besieged by Charles the Bold, duke of Burgundy, was courageously defended by its inhabitants, among whom a woman, Jeanne Laine, celebrated under the name of Jeanne la Hachette, distinguished herself by her intrepidity. Her statue was set up in the city in 1851. The ancient ramparts have been partly levelled and converted into promenades. The cathedral is one of the largest in France, and its choir is a masterpiece of Gothic architecture; the church of St. Etienne is a fine specimen of the renaissance style, and contains famous sculptures and stained windows. The abbey church, prior to the revolution, contained statues of all the Merovingian kings.

The city has important manufactures, especially in silks, carpets, and tapestries.