In the spring of 1706 Turin was preparing to defend itself from siege by the French army which had already taken Nice and the lands of the Savoy. Louis XIV, highly ambitious, aimed to transform Piedmont into a French province. On 12 May of the same year the strong army reached the city of Turin and for four months the city was besieged and bombarded. On 28 August Vittorio Amedeo II and Prince Eugenio of Carignano, commander of the allied Austrian army, met on the hill of Superga to examine the battlefield better from that height. Witnesses reported that the two leaders climbed the hill a second time on 2 September of the same year, and together they entered the little church on the hill, which served as a parish for the few churchgoers living on the hill. On that occasion Holy Communion was celebrated and the Ave Maris Stella was solemnly sung. When they reached the line mostra Te esse Matrem (show us that you’re a mother) Vittorio Amedeo II prostrated himself at the feet of the Virgin Mary and vowed that if he won he would build a magnificent temple dedicated to her on the hill. The two princes went down from the hill and carried out their battle plan. On 7 September the French army was defeated. When the people found out about the duke’s vow, they put the victory down to the intervention of Mary. However, for several years the city, badly hit by the harsh war, did not have the funds to realise the pledge. Only in 1717 did Vittorio Amedeo II, king of Sicily and then of Sardinia, fulfil his vow and lay the first stone of the glorious temple, built in honour of the Virgin Mary, saviour of Turin.
After 14 years, on 1 November 1731 the Basilica was opened to the public in a solemn ceremony attended by King Carlo Emanuele III, son and heir of Vittorio Amedeo II, the architect Filippo Juvarra, who designed the Basilica, fellow victors, and numerous city dignitaries.