Rocca d’Anfo Fortress
Sitting above Lake Idro, the fortress of Rocca d’Anfo was of critical strategic importance for blocking invaders from moving south through the valley linking Trento to Brescia. Built during the Napoleonic Wars, it was the site of many battles but also the location of a revolution in cartography.
Towering more than 300 metres above the dark waters of Lake Idro, the summit tower of the Rocca d'Anfo fortress is often obscured in mist.
During both Italian campaigns, the Austrians used the valley linking Trento to Brescia to outflank the French on the plain of the Po valley. It required the tactical genius of General Bonaparte to overcome them. It became clear that it was vital to control this route, which had long served as a corridor for invaders coming in from the north – attested to by the Gothic helmets and shields that military engineers discovered as they dug temporary entrenchments to hastily fortify the road.
The site was the testing ground for a new method for depicting geographical terrain in relief that involved equidistant contour lines. Developed by Gaspard Monge, the method was applied here by one of his earliest pupils at France’s École Polytechnique, François Haxo.
It fell to the engineer François Liédot to devise a revolutionary project that would put this new cartographic tool to the test. Knowing that troops would move through a system of underground galleries that were invisible to the enemy, he grasped that there was no need to build a continuous enclosure to control the strategic route. Instead, he proposed only occupying positions that were strictly required to observe and bombard it, abandoning Vauban's approach in favour of that of Montalembert.
Since most people, including most in the military, would not have been able to interpret contour lines at the time, he produced a relief model that could be disassembled and moved. The First Consul used it when he decided to build the fortress. It remained unfinished at the end of the First Empire but remains a pivotal testament to the history of both cartography and military architecture.