When Prime Minister Bettino Craxi first thought of having a national holiday to commemorate the Italian flag and the national unity it represents, it seemed a simple enough idea.

Although Italy has a slew of holidays, both religious and patriotic, Craxi had decided that 125 years after the nation was united out of a patchwork of rival kingdoms, principalities, duchies and papal territories, the time had come to pay homage to Italy's unification.

Thus, 10 days ago Craxi's Cabinet approved a decree to commemorate national unity every May 12, the date in 1798 when the Italian red, white and green flag was raised in Milan over the Cisalpine Republic. Created by Bonapartists, the republic united a handful of former Hapsburg duchies along the Po River Valley.

What Craxi seemed to forget was that Italian unity remains fragile to this day. Old rivalries and regional pride die slowly in the Italian countryside.

Hardly was Craxi's decision made, when protests began from the Po Valley city of Reggio Emilia, which, it turns out, calls itself the "city of the tricolor." It claims that the first Italian flag flew there a year and four months before it did over Milan -- that is, on Jan. 7, 1797.

Reggio's Communist mayor, Ugo Benassi, promptly denounced the decision taken by Craxi, a Socialist, and said that if any date was assigned to be national flag day it should be Jan. 7, not May 12.

"We are mad as dogs," Benassi said of the perceived national slight to his municipality.

Others began murmuring darkly about the hidden political significance in the move, alleging that Craxi, a native of Milan, had chosen the date the flag first flew over Milan as the national holiday to help his electoral standing back home.

Editorialists from around the country entered the debate, television programs devoted prime time discussions to it, and historians, politicians and columnists all weighed in to argue the merits of when the holiday should be held and where the flag first flew.

"The Reggionist request for the date change," wrote Mayor Benassi in the Rome daily La Repubblica, "is not inspired by municipal pride, but by the need for historical truth." His counterpart in Milan, Mayor Carlo Tognoli, wrote in another newspaper, "I can personally assure you that there has been no political pressure in favor of the choice" of the May 12 date.

Craxi finally lost patience yesterday and told one of his aides in full hearing of journalists, "I'm fed up with this whole polemic over the tricolor."

"I wanted to have a holiday to celebrate national unity, not open a historical dispute," Craxi said. Convinced that his effort to celebrate unity had only aroused a new wave of disunity, Craxi let it be known today that he was shelving the whole idea -- at least for the moment.

In the meantime, the newspapers today brought up another issue to take the tricolor debate's place: national polls, they said, had established that 52 percent of Italians want to shelve their insipid national anthem in favor of Giuseppe Verdi's march from the opera "Nabucco" that they find more stirring.

Leading that argument, it seems, are the citizens of Parma, Reggio's sister city along the Po, near Verdi's birthplace. Craxi, one of his advisers said privately today, had no intention of getting into that one.