Quadrilateral

Famous combination of four fortresses mutually supporting one another, during the Austrian rule of northern Italy. The four fortified towns were Mantua, Peschiera, Verona, and Legnago, lying between Lombardy and Venetia; the former two were on the Mincio and the latter two on the Adige. The real value of the Quadrilateral, which gave Austria such a firm hold on Lombardy,