High Quality Content by WIKIPEDIA articles! The Catalonia Offensive was part of the Spanish Civil War. The Nationalist Army started the offensive on December 23, 1938, and rapidly conquered Republican-held Catalonia with Barcelona (the Republic`s capital city from October 1937). Barcelona was captured on January 26, 1939. The Republican government headed for the French border. Thousands of people fleeing the Nationalists also crossed the French border in the following month, to be placed in internment camps. Franco closed the border with France by February 10, 1939.