Soon after the Italian unification he formed an army of two thousand men, leading the most cohesive and feared band in Southern Italy and becoming the most formidable leader on the Bourbon side.

Meanwhile, Basilicata's population began to rise against the new government, because it did not get any benefit from the political change and became even poorer than before, while the bourgeois class (faithful to the Bourbons in the past) maintained its privileges, after having supported the cause of the Italian unification opportunistically.

[19] Subsequently Lavello was invaded, where he set up a court which judged 27 liberals and the municipal coffers were emptied of 7,000 ducats, 6,500 of which were distributed to the people[20] and then Melfi.

Crocco's army also conquered parts of Campania (Sant'Angelo dei Lombardi, Monteverde, Conza, Teora),[21] Apulia (Bovino and Terra di Bari).

Meanwhile, another legitimist agent arrived: Augustin De Langlais from France, an ambiguous person about which little is known of his life, including the reason for his presence among the brigands.

[23] Crocco, with the support of Borjes and De Langlais, conquered other towns searching for new recruits, including Trivigno, Calciano, Garaguso, Craco and Aliano.

After other battles and retreating to Monticchio, one of his headquarters, Crocco broke the alliance with Borjes because he did not want to serve under a foreigner and did not believe the promise of the Bourbon government about the provision of reinforcements.

Disappointed, Borjes planned to go to Rome, to inform King Francis II but, during the journey, he was captured in Tagliacozzo and shot by Piedmontese soldiers headed by Major Enrico Franchini.

Without external support, Crocco turned to plundering and extortion to raise funds, cooperating with like-minded confederates and making raids from Molise to Apulia.

Faced with the apparent invincibility of Crocco's army, the Hungarian Legion (who helped Garibaldi during the expedition of the thousand) intervened in support of the royal coalition.

Under the command of General Emilio Pallavicini (known to have stopped Garibaldi's expedition against Rome in the Calabrian mountains), the royal army engaged and defeated Crocco.

His band suffered many casualties, and some of his lieutenants, such as Ninco Nanco and Giuseppe "Sparviero" Schiavone, were captured and executed by firing squad, leaving Crocco to retire toward the Ofanto zone.

After losing the last battle, he was forced to flee to the Papal States, hoping for help from Pius IX, whom he knew had previously supported the southern opposition.

[27] The movie Il Brigante di Tacca del Lupo (1952), directed by Pietro Germi, is vaguely based on Crocco's story.

directed by Pasquale Squitieri, starring Enrico Lo Verso (in the role of Crocco), Claudia Cardinale, Remo Girone, Franco Nero among the others.

[28] He is the main protagonist of the TV film Il generale dei briganti (2012) by Paolo Poeti; Crocco is played by Daniele Liotti.

[29] The Italian actor Michele Placido, born and raised in Apulia to a Lucanian father from Rionero in Vulture and an Apulian mother, claims to be a descendant of Crocco.