Picture from the basilica in Turin Here
Mary is the mother of Jesus and is often referred to by Catholics as Our Lady. Catholics believe that Jesus is the Son of God and is often referred to as Our Lord. The Fathers of the Church referred to Mary as Theotokos (Mother of God) and Boeteia (the Helper). St John Chrysostom used the title Helper in a homily of 345. Some think that Pope St Pius V inserted the title Help of Christians into the litany of Our Lady after the battle of Lepanto (7 October 1571) where the Turks were defeated by the Holy League, which the Pope attributed to the recitation of the rosary. He instituted the feast of Our Lady of Victory on that date, which is now the feast of Our Lady of the Rosary.
In 1815 the feast of Our Lady, Help of Christians was instituted by Pope Blessed Pius VII to be celebrated on May 24, the date he returned to Rome after 3 years of imprisonment by Napoleon at Savona and at Fontainebleau. St. John Bosco, founder of the Salesian Congregation in 1868, dedicated to Our Lady, Help of Christians, the mother church of his congregation at Turin. In 1862, Don Bosco said to a colleague "Our Lady wants us to honour her with the title of Mary, Help of Christians. The times are so sad that we need the Holy Virgin to help us preserve and defend the Christian faith".