The colours of the Italian flag, green, white and red, are thought to have their origin in the colours of the military uniforms of the Duchy of Milan in late 18th century as the Civic Militia wore a green and white uniform. After the French under Napoleon Bonaparte had gained control of northern Italy in 1796, the Transpadane Republic was proclaimed in Milan. The Civic Militia became the National Guard which included red in their uniform.
The French army had also formed the Cispadane Republic from the provinces of Modena, Bologna, Ferrara and Reggio Emilia south of the Po river and it is here the first flag in the "Italian" colours was hoisted, on 7 January 1797: a horizontal tricolour of red-white-green with the republican arms in the centre. The Transpadane Republic adopted a vertical tricolour of green-white-red. On 30 June 1797 Cispadana and Transpadana were merged with the province of Novara and the Cisalpine Republic was created by the French. Cisalpina adopted a flag on 11 May 1798 which was a square vertical tricolour, clearly influenced by the flag of revolutionary France and it is claimed that changing the blue of the French flag to green was Napoleon's decision. Italy's national colours were hereby confirmed.
The constitution of the Cisalpine Republic was changed on 26 January 1802, to allow the French First Consul, Napoleon Bonaparte himself, to become its president and the country's name was changed to Italian Republic. The design of the flag was changed to a red square with a white rhombus and a small green square in the middle of the rhombus. It was adopted on 20 August 1802. Three years later, on 17 March 1805 it became the Kingdom of Italy and Napoleon was crowned as its king in the Cathedral of Milan. The flag stayed the same, although its proportions could be changed to 2:3 and Napoleon's eagle was placed in the centre of the green rectangle as his standard. It ended on 11 April 1814 with Napoleon's defeat and exile to the island of Elba.
On 17 March 1861 the drive for unification of Italy succeeded with the proclamation of the Kingdom of Italy under Victor Emmanuel II from the House of Savoy, who had ruled the Kingdom of Sardinia from 1849. Its flag had been blue with at upper hoist a red square with a white cross; upon unification it adopted the green-white-red tricolour with in the centre the arms of the house of Savoy, a blue-bordered red shield with a white cross. This arms was removed when, after the Second World War the monarchy was abolished and the Italian Republic proclaimed, adopting the present green-white-red flag.
The 20 regions of Italy have all adopted a "gonfalon" or "gonfanon", a type of heraldic flag or banner, suspended from a crossbar. This has been made into a regular flag, although not all of these are official.