He is the fourth-longest serving Prime Minister in Italian history, after Benito Mussolini, Giovanni Giolitti and Silvio Berlusconi, and at the time of his death he was the longest-served.

Depretis is widely considered one of the most powerful and important politicians in Italian history, having enacted numerous reforms that modernized Italy, such as expanding male suffrage and free education.

The project was an ambitious and risky venture aiming to conquer, with a thousand men, a kingdom with a larger regular army and a more powerful navy.

[7] In 1860 Depretis went to Sicily on a mission to reconcile the policy of Cavour, who desired the immediate incorporation of the island in the Kingdom of Italy, with that of Garibaldi, who wished to postpone the Sicilian plebiscite until after the liberation of Naples and Rome.

Rattazzi's policy of repression towards Garibaldi at Aspromonte, caused lot of public protests and the Prime Minister was forced to resign in September 1862.

[11] Depretis remained on the sidelines during the 8th legislature (1863–65), but he regularly participated in the parliamentary works, intervening regarding the laws for administrative unification and declaring himself hostile to regionalism.

But he also refused to give to admiral Persano detailed orders about the expedition in the Adriatic Sea against the fleet led by Wilhelm von Tegetthoff.

To quell the public outcry after the two defeats, Depretis called for process Persano, who was judged by the Italian Senate, condemned for incompetence in 1867 and cashiered from duty.

His tenure as minister was quite controversial; his apologists contend, however, that, as an inexperienced civilian, he could not have made sudden changes in naval arrangements without disorganizing the fleet, and that in view of the impending hostilities he was obliged to accept the dispositions of his predecessors.

Minghetti and Sella were involved into an ambitious program of budget which needed a strong majority, for which they tried to oblige the Independents to choose their side, beginning to build a two-party system as in the United Kingdom.

Prominent ministers were Giovanni Nicotera, Pasquale Stanislao Mancini, Michele Coppino, Giuseppe Zanardelli and Benedetto Brin.

On the other hand, while maintaining the electoral promises, Depretis raised the minimum exemption for the mobile wealth tax from 250 to 800 lire, granting greater deductions for industrial income.

The government however had to face the violent attacks against the Minister of the Interior Nicotera, who was considered guilty, according to a part of the majority, of abuses and illegality; unable to cope with the crisis, Depretis decided to resign in December 1877.

On 11 March 1878, Depretis resigned from his office, when his candidate lost the election to become president of the Chamber of Deputies; the following cabinet was led by another prominent leftist member Benedetto Cairoli.

In the same period, a general irritation was caused by Cairoli and Count Corti's policy of clean hands at the Berlin Congress, where Italy obtained nothing, while Austria-Hungary secured a European mandate to occupy Bosnia and Herzegovina.

Following the French occupation of Tunis on 11 May 1881, in view of popular indignation Cairoli resigned in order to avoid making inopportune declarations to the Chamber.

The king, after the failed attempt by Quintino Sella to establish a new cabinet, appointed Depretis once again prime minister to form his third government.

On 20 May 1882, Depretis signed the Triple Alliance, a secret military agreement between Italy, Germany and Austria-Hungary to oppose the power of France and Russia.

During his long tenure Depretis recomposed his cabinet four times, first throwing out Giuseppe Zanardelli and Alfredo Baccarini in order to please the Right, and subsequently bestowing portfolios upon Cesare Ricotti-Magnani, Robilant and other Conservatives, so as to complete the political process known as Trasformismo.

[8] Depretis also completed the railway system and initiated colonial policy by the occupation of Massawa; but, at the same time, he increased indirect taxation, corrupted the parliamentary parties, and, by extravagance in public works, impaired the stability of Italian finance.

Depretis was the founder and the main proponent of Trasformismo ("Transformism"), a method of making a flexible centrist coalition of government which isolated the extremes of the left and the right.

Indeed, actual governing did not seem to be happening at all, but since only 2 million men had franchises, most of these wealthy landowners did not have to concern themselves with such things as improving the lives of the people they were supposedly representing democratically.

This system brought almost no advantages, illiteracy remained the same in 1912 as before the unification era, and backward economic policies, combined with poor sanitary conditions, continued to prevent the country's rural areas from improving.