Greene first gained power in the local chapter of the International Longshoremen's Association (ILA), where he was elected president during the early 1960s.

Greene set up his own crew called the Celtic Club, complete with enforcers and a close alliance with outlaw biker gangs.

[1] During the 1970s, Greene allied with mob-affiliated labor union leader John Nardi during the latter's war against Jack Licavoli for leadership of the Cleveland family.

A police investigation revealed that Greene's murder had been a criminal conspiracy between the Mafia families of Cleveland, New York City and Southern California.

The investigation also resulted in the defections of Ray Ferritto and Los Angeles boss Jimmy Fratianno, followed by the exposure and arrest of a mole inside the Cleveland FBI.

Unable to provide for Danny, his father placed him in Parmadale, a Roman Catholic orphanage in Parma, Ohio, three miles outside Cleveland.

There he frequently fought with Italian-American students, children of more recent immigrants struggling for a place, and he developed an intense dislike for Italians that lasted his entire life.

He was also expelled from Collinwood High School, in that case, due to excessive tardiness, which he claimed was caused by the bullying of fellow students.

[citation needed] After being expelled from Collinwood High School in 1951, Greene enlisted in the United States Marine Corps, where he was soon noticed for his abilities as a boxer and marksman.

Greene led sometimes violent protests and strikes to force the stevedore companies to allow the ILA to oversee the hiring of dockworkers.

"[citation needed] As a union organizer, Greene sometimes declared work stoppages, as frequently as 25 per day, to demonstrate to company owners his authority on the docks.

After Sam Marshall, an investigative reporter, collected affidavits that supported charges of extortion, Greene was exiled from the union and convicted of embezzlement.

Rather than face a second trial, Greene pleaded guilty to the lesser charge of falsifying union records, was fined $10,000, and received a suspended sentence.

The series brought Greene unwanted attention from the U.S. Attorney, the Internal Revenue Service, the Labor Department, and the Cuyahoga County prosecutor.

For example, in May 1968, under Birns's orders, Greene was supposed to attack a black numbers man who was holding out on protection money due.

Cleveland police later learned Frato was armed and had an opportunity to kill Greene several weeks prior to the White Beach shooting.

Journalist Ned Whelan wrote about Greene: "Imagining himself as a feudal baron, he supported a number of destitute Collinwood families, paid tuition to Catholic schools for various children and, like the gangsters of the Twenties, actually had 50 twenty-pound turkeys delivered to needy households on Thanksgiving.

Greene evicted a bookmaker who operated out of a small Waterloo business, and kept a local bar in order by making personal visits.

[citation needed] Greene formed his own crew of young Irish-American gangsters, called "The Celtic Club".

[citation needed] Several minor underworld characters, burglars by trade, took the contract, but their numerous assassination attempts on Greene failed.

Not long afterward, Greene found an unexploded bomb in his car when he pulled into a Collinwood service station to get gas.

In 1975, Greene began to push into the vending machine racket, traditionally controlled by the Mafia, as well as muscled into gambling operations.

[citation needed] In Greene's competition with the Mafia to build a vending machine empire, John Conte became a victim.

In 1976, longtime mobster John Scalish died, leaving control of Cleveland's lucrative criminal operations, specifically the city's Teamsters Union locals, up for grabs.

His bravado and flamboyant behaviour only added to his growing aura of invincibility and power in the urban legends of the Cleveland criminal underworld.

"[citation needed] On May 17, 1977, Greene's longtime ally John Nardi was killed by a bomb,[23] planted by Pasquale Cisternino and Ronald Carabbia.

Shortly after their meeting, Greene muscled in on a large West Side gambling operation originally run by Nardi.

The plan to assassinate him was orchestrated by members of these families, with key figures such as James "Jack White" Licavoli and Angelo "Big Ange" Lonardo playing significant roles.

"[31] In return for his testimony, he pleaded guilty to the murder charges and received a five-year prison sentence, of which he served 21 months.

[30] In 1980, after testifying for the government that led to the racketeering convictions of five reputed Mafia figures, Fratianno entered the federal Witness Protection Program.