ILLE-ET-VILAINE, a maritime department of north-western France, formed in 1790 out of the eastern part of the old province of Brittany. Pop. (1906) 611,805. Area 2699 sq. m. It is bounded N. by the English Channel, the Bay of St Michel and the department of Manche; E. by Mayenne; S. by Loire-Inférieure; and W. by Morbihan and Côtes-du-Nord. The territory of Ille-et-Vilaine constitutes a depression bordered by hills which reach their maximum altitudes (over 800 ft.) in the N.E. and W. of the department. The centre of this depression, which separates the hills of Brittany from those of Normandy, is occupied by Rennes, capital of the department and an important junction of roads, rivers and railways. The department takes its name from its two principal rivers, the Ille and the Vilaine. The former joins the Vilaine at Rennes after a course of 18 m. through the centre of the department; and the latter, which rises in Mayenne, flows westwards as far as Rennes, where it turns abruptly south. The stream is tidal up to the port of Redon, and is navigable for barges as far as Rennes. The Vilaine receives the Meu and the Seiche, which are both navigable. There are two other navigable streams, the Airon and the Rance, the long estuary of which falls almost entirely within the department. The Ille-et-Rance canal connects the town of Rennes with those of Dinan and St Malo. The greater portion of the shore of the Bay of St Michel is covered by the Marsh of Dol, valuable agricultural land, which is protected from the inroads of the sea by dykes. Towards the open channel the coast is rocky. Small lakes are frequent in the interior of the department. The climate is temperate, humid and free from sudden changes. The south-west winds, while they keep the temperature mild, also bring frequent showers, and in spring and autumn thick fogs prevail. The soil is thin and not very fertile, but has been improved by the use of artificial manure. Cereals of all kinds are grown, but the principal are wheat, buckwheat, oats and barley. Potatoes, early vegetables, flax and hemp are also largely grown, and tobacco is cultivated in the arrondissement of St Malo. Apples and pears are the principal fruit, and the cider of the canton of Dol has a high reputation. Cheese is made in considerable quantities, and the butter of Rennes is amongst the best in France. Large numbers of horses and cattle are raised. Mines of iron, lead and zinc (Pont-Péan) and quarries of slate, granite, &c., are worked. There are flour and saw-mills, brick works, boat-building yards, iron and copper foundries and forges, dyeworks, and a widespread tanning industry. Sail-cloth, rope, pottery, boots and shoes (Fougères), edge-tools, nails, farming implements, paper and furniture are also among the products of the department. The chief ports are St Malo and St Servan. Fishing is very active on the coast, and St Malo, St Servan and Cancale equip fleets for the Newfoundland cod-banks. There are also important oyster-fisheries in the Bay of St Michel, especially at Cancale. The little town of Dinard is well known as a fashionable bathing-resort. Exports include agricultural products, butter, mine-posts and dried fish; imports, live-stock, coal, timber, building materials and American wheat. The department is served by the Western railway, and has over 130 m. of navigable waterway. The population is of less distinctively Celtic origin than the Bretons of Western Brittany, between whom and the Normans and Angevins it forms a transitional group. Ille-et-Vilaine is divided into the arrondissements of Fougères, St Malo, Montfort-sur-Meu, Redon, Rennes and Vitré, with 43 cantons and 360 communes. The chief town is Rennes, which is the seat of an archbishop and of a court of appeal, headquarters of the X. army corps, and the centre of an académie (educational division).
In addition to the capital, Fougères, St Malo, St Servan, Redon, Vitré, Dol, Dinard and Cancale are the towns of chief importance and are separately noticed. At Combourg there is a picturesque château of the 14th and 15th centuries where Chateaubriand passed a portion of his early life. St Aubin-du-Cormier has the ruins of an important feudal fortress of the 13th century built by the dukes of Brittany for the protection of their eastern frontier. Montfort-sur-Meu has a cylindrical keep of the 15th century which is a survival of its old ramparts.