It was only when I came to Rome that I discovered that March 17th is celebrated with solemnity in the Hungarian diocese of Gyor. The full story is told here.
In brief, William Lynch the Catholic Bishop of the tiny diocese of Clonfert fled to Europe in the 17th Century and finally ended up in Hungary - at Gyor to be precise. Appointed an auxiliary of the diocese he laboured there for 10 years until his death. In his will he left an image of the Madonna which he brought from his own Cathedral to that of Gyor. The article explains:
The people of Gyor and its vicinity admired the picture, which came from a faraway land and felt it was divine intervention that had brought and left the treasured relic in their custody. Her arrival had marked a series of their victories over the Turks, and during the years many came to pray before the Madonna; it was felt that many national disasters had been averted through her intercession.
In 1697 the Hungarians enjoyed greater peace than they had known for many years. But during that year in Ireland, a greater blow than ever was to fall upon Bishop Lynch's coreligionists. In that year Parliament passed an edict that all priests were to be expelled from the territory of Ireland and from all the British Isles, the churches confiscated and all traces of the Catholic religion wiped out. A national Irish church was established and the dead could only be buried by ministers of that religion.
On March 17, 1697, Saint Patrick's Day, as thousands were praying during early morning Mass in the Cathedral of Gyor, priests and faithful suddenly saw that the eyes of the Madonna on the picture donated by the Irish prelate were shedding tears and blood, which dropped down upon the Child in the crib over which she was bending. This miracle lasted more than three hours. The face of the Madonna was wiped with linen (this linen is still preserved in the Cathedral of Gyor), but the blood and tears did not cease to flow. The picture was immediately taken from the wall and removed from its frame; the phenomenon continued. News of the marvel immediately spread to the far corners of the city and not only Catholics, but Protestants and Jews flocked to see the miracle. It was witnessed by thousands, and many of them gave testimony of what they saw. A document signed by more than a hundred persons bears the signature of the imperial governor of the city, the mayor, all the councilmen, the Bishop, some priests, Calvinist and Lutheran ministers and a Jewish rabbi--all of whom, volunteered to give their testimony to an undeniable fact.