Since the autumn of 1942 the big bombings cycle on Turin began and it highlighted dramatically the precariousness of the city's defensive measures and the scarcity of adequate air-raid shelters. Proof of this is that over a year after the start of the war thousands of linear meters of trenches were excavated on the city ground in order to defend the population from enemy incursions, and only in December 1941 they were demolished due to the complete ineffectiveness . Summing up the capacity of all the shelters in Turin, private and public, it appears that only 15% of the population could be considered sheltered during the bombing.