Saint John Chrysostom was the first person to use the Marian title Sancta Maria Auxilium, or Mary, Help of Christians, in A.D. 345 as a devotion to the Virgin Mary, along with Saint Don Bosco, who also propagated the same Marian devotion under this title. It was established due to the great appreciation of Saint Don Bosco for this Marian title and the development of the Salesian works in several countries since the second half of the 19th century.
The title of Mary Help of Christians is associated with the defense of Christian Europe (Latin and Greek), the north of Africa and the Middle East from non-Christian peoples during the Middle Age. In 1572, the Islamic Ottoman Empire intended to invade Christian Europe. Pope Pius V called Christian armies from all over Europe to defend the continent and asked the believers to pray to Mary in order to help the Christians. The defeat of the Muslim Turks was attributed to the intercession of Mary under this title.
In May 24, 2009, during his Regina Cæli papal address, Pope Benedict XVI invoked this Marian patronage, under the venerated title of Our Mother of Sheshan, calling for Chinese Catholics calling them to renew their fidelity to the Pope as the sole successor of Saint Peter.
There are two inscriptions of the first centuries of Christianity in Greek related to the Virgin Mary: Θεοτοκος (Theotokos, or Mother of God) and Βοετεια (Boeteia, the Helper). The Fathers of the Church referred to Mary as “Βοετεια.” John Chrysostom used the title in a homily of 345, Proclus in 476 and Sebas of Cæsarea in 532. After the Patristic period (5th century), other persons used it like Romano Melone in 518, the Patriarch of Jerusalem, Sophronius in 560, John of Damascus in 749 and German of Constantinople in 733.
Around 1576, Bernardino Cirillo, archpriest of Loreto, published at Macerata two litanies of the Blessed Virgin, which, he contended, were used at Loreto. One is in a form which is entirely different from our present text. Another form (“Aliæ litaniæ B.M.V.”) is identical to the litany of Loreto approved by Pope Clement VIII in 1601 and now used throughout the entire Church. This second form contains the invocation Auxilium Christianorum. Possibly the warriors, who returning from the Battle of Lepanto (October 7, 1571) visited the sanctuary of Loreto, saluted the Holy Virgin there for the first time with this new title. It is more probable, however, that it is only a variation of the older invocation Advocata Christianorum, found in a litany of 1524.
The feast of Our Lady, Help of Christians, was instituted by Pope Pius VII. By order of Napoleon I of France, Pius VII was arrested on June 5, 1808, and detained a prisoner for three years at Savona, and then at Fontainebleau. In January 1814, after the battle of Leipzig, he was brought back to Savona and set free on March 17, on the eve of the feast of Our Lady of Mercy, the Patroness of Savona. The journey to Rome was a veritable triumphal march. The pontiff, attributing the victory of the Church after so much agony and distress to the Blessed Virgin, visited many of her sanctuaries on the way and crowned her images (e.g., the “Madonna del Monte” at Cesena, “della Misericordia” at Treja, “della Colonne” and “della Tempestà” at Tolentino). The people crowded the streets to catch a glimpse of the venerable pontiff who had so bravely withstood the threats of Napoleon. He entered Rome on May 24, 1814, and was enthusiastically welcomed.
When Napoleon left Elba and returned to Paris, Murat was about to march through the Papal States from Naples; Pius VII fled to Savona on 22 March, 1815. After the Congress of Vienna and the battle of Waterloo, the Pope returned to Rome on July 7, 1815. To gave thanks to God and Our Lady, on 15 September 1815 he declared 24 May, the anniversary of his first return, to be henceforth the feast of Our Lady, Help of Christians; the 1913 Catholic Encyclopedia article mentions that it has spread nearly over the entire Latin Church, but is not contained in the universal calendar.
The Marian feast was celebrated by the order of Servites since the 17th century. Pope Pius VII extended the feast of the Seven Dolours of Mary to the universal Church on September 18, 1814. The veneration to Mary became popular under this title in Rome especially, where the feast was especially promulgated by Saint John Bosco and Saint Vincenzo Palotti. St. John Bosco was an ardent promoter of devotion to “Mary, Help of Christians.” He even built a huge Basilica in her honor in 1868 and founded a religious Congregation for women, under the title of, “The Daughters of Mary, Help of Christians.”