Northern Italy had been contested by France and the Habsburgs for centuries, since it was vital for control of South-West France, an area with a long history of opposition to the central authorities. While Spain remained the dominant power in Italy, its reliance on long exterior lines of communication was a potential weakness, especially the Spanish Road; this overland route allowed them to move recruits and supplies from the Kingdom of Naples through Lombardy to their army in Flanders. The French sought to disrupt the Road by attacking the Spanish-held Duchy of Milan or blocking the Alpine passes through alliances with the Grisons.