For 50 years through World War II, French-speaking Wallonia was a technically advanced, industrial region, with its industry concentrated along the sillon industriel, while Dutch-speaking Flanders was predominantly agricultural with some industry, mainly processing agricultural products and textiles. This disparity began to fade during the interwar period. When Belgium emerged from World War II with its industrial infrastructure relatively undamaged thanks to the Galopin doctrine, the stage was set for a period of rapid development, particularly in Flanders. The postwar boom years, enhanced by the establishment of the European Union and NATO headquarters in Brussels, contributed to the rapid expansion of light industry throughout most of Flanders, particularly along a corridor stretching between Brussels and Antwerp, which is the second largest port in Europe after Rotterdam.