<P> In February 1848, there were revolts in Tuscany that were relatively nonviolent, after which Grand Duke Leopold II granted the Tuscans a constitution . A breakaway republican provisional government formed in Tuscany during February shortly after this concession . On 21 February, Pope Pius IX granted a constitution to the Papal States, which was both unexpected and surprising considering the historical recalcitrance of the Papacy . On 23 February 1848, King Louis Philippe of France was forced to flee Paris, and a republic was proclaimed . By the time the revolution in Paris occurred, three states of Italy had constitutions--four if one considers Sicily to be a separate state . </P> <P> Meanwhile, in Lombardy, tensions increased until the Milanese and Venetians rose in revolt on 18 March 1848 . The insurrection in Milan succeeded in expelling the Austrian garrison after five days of street fights--18--22 March (Cinque giornate di Milano). An Austrian army under Marshal Josef Radetzky besieged Milan, but due to defection of many of his troops and the support of the Milanese for the revolt, they were forced to retreat . </P> <P> Soon, Charles Albert, the King of Sardinia (who ruled Piedmont and Savoy), urged by the Venetians and Milanese to aid their cause, decided this was the moment to unify Italy and declared war on Austria (First Italian Independence War). After initial successes at Goito and Peschiera, he was decisively defeated by Radetzky at the Battle of Custoza on 24 July . An armistice was agreed to, and Radetzky regained control of all of Lombardy - Venetia save Venice itself, where the Republic of San Marco was proclaimed under Daniele Manin . </P> <P> While Radetzky consolidated control of Lombardy - Venetia and Charles Albert licked his wounds, matters took a more serious turn in other parts of Italy . The monarchs who had reluctantly agreed to constitutions in March came into conflict with their constitutional ministers . At first, the republics had the upper hand, forcing the monarchs to flee their capitals, including Pope Pius IX . </P>

What concept played the biggest role in the unification of italy and germany