By 1345, the Hundred Years' War between France and England had been going on for only about eight years. The English claimed the right to the French throne, and the French refused to be ruled by foreigners. In August the English Earl of Derby commenced the Gascon campaign of 1345, taking a large French army at Bergerac, Dordogne by surprise and decisively defeating it. Later in the campaign, on 21 October the French were besieging the castle at Auberoche, when Derby's army caught them off guard during their evening meal and won one of the most decisive battles of the war. This set the stage for English dominance in the area for several years. Previous to this, the French had been having success, and the English had even offered a treaty, but with this battle along with Derby's overrunning of the Agenais (lost twenty years before in the War of Saint-Sardos) and Angoulême, as well as the forces in Brittany under Sir Thomas Dagworth also making gains, the tide turned somewhat in this year.