ancient province (pays) of western France, corresponding to the northern part of the modern département of Charente-Maritime with the southern part of Deux-Sèvres. Subjected, from the 10th century on, to the counts of Poitiers, Aunis shared the political fortunes of neighbouring Poitou. In the pre-Revolutionary period it constituted, together with the islands of Ré and Oléron, a military gouvernement with headquarters at La Rochelle.