On August 21, 1879, at about 7 pm, Mary McLoughlin, 45, housekeeper to Archdeacon Kavanagh, went to the nearby cottage of Mary Byrne, 29. On the way, she passed by the south gable of the parish church. Miss McLoughlin reported,
"On passing by the chapel, and at a little distance from it, I saw a wonderful number of strange figures or appearances at the gable; one like the Blessed Virgin Mary, and one like St. Joseph; another a bishop; I saw an altar."
Miss McLoughlin thought that possibly the Archdeacon had been supplied with the figures from Dublin or elsewhere, and passed on to the home of the widow Margaret Byrne and her children, where she said nothing initially of her vision.
After half an hour, Mary McLoughlin returned to the church with Miss Mary Byrne to lock up the church. There they beheld the vision. Mary Byrne went to fetch her brother Dominick Byrne, 20. Mr. Byrne, who worked as an assistant to Archdeacon Kavanagh, was resting at the time after working in the fields. Then she sent her niece, Catherine Murray, 8, who was staying with them, to fetch her mother, Mrs. Margaret Byrne, and her sister Miss Margaret Byrne, 21.
The Byrnes alerted some of their neighbours to the apparition. Dominick Byrne ran to the home of his cousin, Dominick Byrne, Sr., who came with Patrick Hill, 13, a servant boy, John Durkan, 24, and a little boy called John Curry, six years old. Dominick Byrne also called to the house of Patrick Byrne, 16, who came and saw the apparition. Mary Byrne called to the home of Judith Campbell, 22, who also witnessed the apparition, as did Bridget Trench, 74 or 75 years old, who gave a vivid account of the apparition in Irish.
Those who witnessed the apparition stood in the pouring rain for up to two hours reciting the Rosary, a traditional Catholic prayer. When the apparition began there was good light, but although it then became very dark, witnesses could still see the figures very clearly - they appeared to be the colour of a bright whitish light. The apparition did not flicker or move in any way. The witnesses reported that the ground around the figures remained completely dry during the apparition although the wind was blowing from the south. Afterwards, however the ground at the gable became wet and the gable dark.
Two other people also witnessed the apparition, although they did not realise its significance until later. Mrs. Hugh Flatley, 44, who happened to pass by the church at 8 pm and thought the parish priest "had been ornamenting the church, and got some beautiful likenesses removed outside." Patrick Walsh was working on his land around 9 pm some half a mile from the church:
"I saw a very bright light on the southern gable end of the chapel; it seemed to me to be a large globe of golden light; I never saw, I thought, so brilliant a light before; it appeared high up in the air above around the chapel gable and it was circular in appearance; it was quite stationary, and it seemed to retain the same brilliancy all through."
Altogether, the accounts of the apparitions provided the following details. Virgin Mary, her husband St. Joseph, and St. John the Evangelist appeared at the south gable end of the local small parish church, the Church of St. John the Baptist. Behind them and a little to the left of St. John was a plain altar. On the altar was a cross and a lamb (a traditional image of Jesus, as reflected in the religious phrase The Lamb of God) with adoring angels.
The Virgin Mary was described as being life size, standing about two feet above the ground. She wore a white cloak, hanging in full folds and somewhat loosely around the shoulder, and fastened at the neck. She wore a crown, and over the forehead and where the crown fitted the brow, a beautiful rose. The crown appeared brilliant, and of a golden brightness, of a deeper hue than the striking whiteness of the robe she wore; the upper parts of the crown appeared to be a series of sparkles or glittering crosses. She was described as "deep in prayer", with her eyes raised to heaven, her hands raised to the shoulders or a little higher, the palms inclined slightly to ths shoulders. Bridget Trench "went in immediately to kiss, as I thought, the feet of the Blessed Virgin; but I felt nothing in the embrace but the wall, and I wondered why I could not feel with my hands the figures which I had so plainly and so distinctly seen."
St. Joseph, also wearing white robes, stood on the Virgin's right hand. His head was bent forward from the shoulders towards the Blessed Virgin in respect. He appeared somewhat aged with grey whiskers and greyish hair. St. John the Evangelist stood to the left of the Blessed Virgin. He was dressed in a long robe and wore a mitre. He was partly turned away from the other figures. He appeared to be preaching and he held open a large book in his left hand. His right hand was raised with the index and middle fingers straight and the ring and little fingers bent double, with the thumb placed against the hoints of them next the tips.
To the left of St. John was an altar with a lamb standing with a cross. Around the altar angels hovered the whole time, their wings fluttering.
An ecclesiastical commission of inquiry was established by the Archbishop of Tuam, Most Rev. Dr. John MacHale. The Commission's final verdict was that the testimony of all the witnesses taken as a whole is trustworthy and satisfactory. At a second Commission of inquiry in 1936, the surviving witnesses confirmed the evidence they gave to the first Commission.
The growth of railways and the appearance of local and national newspapers fueled interest in what had up to then been a small Mayo village. Reports of "strange occurrences in a small Irish village" were featured almost immediately in the international media, notably The Times of London. Newspapers from as far away as Chicago sent reporters to cover the Knock phenomenon, while Queen Victoria asked her government in Dublin Castle to send her a report about the event. In later years, Catholic nationalists used the apparition to symbolically challenge Queen Victoria's authority in Ireland by dubbing Our Lady of Knock "Queen of Ireland."
Though it remained for almost 100 years a major Irish pilgrimage site, Knock established itself as a world religious site especially during the last quarter of the twentieth century, largely due to the work of its longterm parish priest, Monsignor James Horan. Horan presided over a major rebuilding of the site, with the provision of a new large Basilica (the first in Ireland) alongside the old church, which could no longer cope with visitor numbers.
In 1979, the centenary of the apparition, Pope John Paul II, a strong personal devotee of the Virgin Mary, visited Knock Shrine and stated that it was the goal of his Irish visit. On this occasion he presented a Golden Rose, a seldom bestoyed token of papal honour and recognition. Mother Teresa of Calcutta visited the Shrine in June of 1993.
Today, Knock Shrine attracts over 1.5 million visitors annually and is western Ireland's most popular attraction.