The title Help of Christians — Auxilium Christianorum — is one of the oldest in the Litany of Loreto; Pius VII instituted its feast on 24 May in 1815, in thanksgiving for his return to Rome after captivity under Napoleon. When the bishops of Australia met for their first Provincial Synod in Sydney in 1844, under Polding, they began with a Votive Mass of Our Lady under that title and petitioned Rome for her recognition as patroness of the country. 'Formal approbation arrived in 1852,' as Cardinal Edward Clancy put it in 1988 — the decree itself has not been traced for this entry.
Of St. Mary's Cathedral in Sydney, the mother church of the country, Cardinal Clancy said that its first builder, Fr. John Joseph Therry, seems to have meant it to be dedicated to her. The bishops rededicated Australia to her on 10 April 1988, in the Marian Year, and again in 2001. In May 2020, with the country shut by the pandemic, they entrusted Australia to Mary Help of Christians, asking her intercession 'for the safety of all our people'.
This is a patronage, not an apparition or a miracle; it is on the map because it is how the Church in Australia commends itself to Our Lady, and where it does so.