
The Colle di Nava blockade was built between 1880 and 1888, to prevent transit on the easy pass that connects the Valle Tanaro with the Valle Arroscia. The square had five forts: the Central Fort and the Bellarasco Fort near the pass, the Richermo Fort on the left, the Pozzanghi Fort and the Montescio Fort on the right (at a considerable distance from the other works), as well as a series of semi-permanent field batteries. The armament was small and medium calibre in all the forts.[Le Fortificazioni delle Alpi del Mare, pp.49-50]