The Siege of Saint-Martin-de-Ré, also Siege of St. Martin's (French:Siège de Saint-Martin-de-Ré), was an attempt by English forces under George Villiers, the Duke of Buckingham to capture the French fortress-city of Saint-Martin-de-Ré, on the isle of Ré (near La Rochelle), in 1627. After three months of siege the Marquis de Toiras and a relief force of French ships and troops managed to repel the Duke, who was forced to withdraw in defeat. This encounter followed another defeat for Buckingham, the 1625 Cádiz Expedition, and is considered to be the opening conflict of the Anglo-French War of 1627-1629, itself a part of the Thirty Years' War.