During the Second Mafia War in the early 1980s, the Corleonesi clan opposed the faction of the Palermitans represented, among others, by Gaetano Badalamenti, Stefano Bontate and Salvatore Inzerillo.

[2] Leggio was linked to the murder of the General Attorney of Sicily, Pietro Scaglione, who was shot dead on 5 May 1971 with his police bodyguard Antonino Lo Russo.

The Corleonesi's primary rivals were Stefano Bontade, Salvatore Inzerillo and Tano Badalamenti, bosses of various powerful Palermo Mafia families.

However, not long after arriving, on 3 September 1982, he was gunned down in the city centre with his wife, Emanuela Setti Carraro, and his driver bodyguard, Domenico Russo.

In response to public disquiet about the failure to effectively combat the organisation Riina headed, La Torre's law was passed ten days later.

[7] This was followed by the deaths of his brother Vincenzo, son-in-law Giuseppe Genova, brother-in-law Pietro and four of his nephews, Domenico and Benedetto Buscetta, and Orazio and Antonio D 'Amico.

[14] Buscetta helped judges Falcone and Paolo Borsellino achieve significant success in the fight against organized crime that led to 475 Mafia members indicted, and 338 convicted in the Maxi Trial.

[15] In an attempt to divert investigative resources away from Buscetta's key revelations, Riina ordered a terrorist-style atrocity, the 23 December 1984 Train 904 bombing; 17 people were killed and 267 wounded.

It was only several years later, when police stumbled on explosives of the same type as used in Train 904 while searching the hideout of Giuseppe Calò, that it became apparent that the Mafia had been behind the attack.

[15] Riina pinned his hopes on the lengthy appeal process that had frequently set convicted mafiosi free, and he suspended the campaign of murders against officials while the cases went to higher courts.

When the convictions were upheld by the Supreme Court of Cassation in January 1992,[17][18] the council of top bosses headed by Riina reacted by ordering the assassination of Salvatore Lima (on the grounds that he was an ally of Giulio Andreotti), and Giovanni Falcone.

News reports in May 2019, indicated that a Cosa Nostra insider revealed that John Gotti of the Gambino crime family had sent one of their explosives experts to Sicily to work with the Corleonesi.

"It may be that the Gambinos at a certain point recognised that the Corleonesi had been victorious in the war between rival families in Sicily ... there is nothing unusual in the traffic of personnel and ideas across the Atlantic ... they were cousin organisations," according to John Dickie, professor of Italian studies at University College London and the author of Mafia Republic – Italy’s Criminal Curse.

[23][24][25] After Riina's capture, a division emerged among the Corleonesi, and a series of bombings occurred by the Corleonesi against several tourist spots on the Italian mainland — the Via dei Georgofili bombing in Florence, Via Palestro massacre in Milan and the Piazza San Giovanni in Laterano and Via San Teodoro in Rome, which left 10 people dead and 93 injured as well as severe damage.

He followed the simple codes of the brutal, ancient world of the Sicilian countryside, where force is the only law and there is no contradiction between personal kindness and extreme ferocity.