When England’s King Henry VIII needed something–or someone–dealt with, he turned to Thomas Cromwell. This man of low birth ascended to power among the devious royal elite of Tudor England and become the mercurial monarch’s most trusted advisor, problem solver and hatchet man.

Considered one of the most astute political minds of the 16th century, Cromwell masterminded some of the most sweeping changes in British history—most notably breaking England away from the Roman Catholic Church and modernizing British government. All the while, he served as a brutal enforcer of Henry VIII’s wishes. He engineered the annulment of the king’s first marriage to Catherine of Aragon through a revolutionary change in England’s religion. And he orchestrated the execution of Henry’s second wife Anne Boleyn because she had failed to produce a male heir.

“The men and women who dared to defy Thomas Cromwell rarely noticed when he laid in wait to destroy them,” writes historian Caroline Angus in My Hearty Commendations: The Transcribed Letters and Remembrances of Thomas Cromwell. That’s because, when it came to carrying out the king’s will, she says, Cromwell proved both “charming” and “ruthless.”

The actual body count of people Cromwell had to dispose of isn’t exactly known. But, as the king’s right-hand man, Angus tells HISTORY.com, he was likely responsible for the deaths of hundreds of people and the imprisonment of countless more.

Bottom line: Cromwell was extremely loyal. “I think that is something we can’t understand today, that someone would go to such a length for somebody else,” says Angus, author of several novels and nonfiction books about the enigmatic historical figure. “The king says, ‘Kill my wife,’ and he goes and does that. That’s extreme.”

But he also likely knew the consequences of defying the king’s wishes—and that he himself was walking a tightrope. “It would be his head on the block instead of theirs,” says Angus. “And Henry would find someone else to kill them anyway.”

Did Cromwell ever express remorse? Not in the historical record. The few times he did speak about Anne after she died, Angus notes, he said she was very intelligent and couldn’t be faulted. But he never admitted any wrongdoing

in having her killed. “I’ve never found anything where he said, ‘We shouldn’t have done that,’” she says.

Born a commoner circa 1485 in the village of Putney, now part of London, Cromwell admitted to being a “ruffian” and having been imprisoned as a youth. Around 1500, he left England for Italy, where he became a mercenary for the French army. Afterward, he worked in the cloth trade for a wealthy Florentine family, then set up shop back in London as a merchant and lawyer.

Cromwell soon came to the attention of the powerful Cardinal Wolsey, Lord High Chancellor under Henry VIII. He served successfully as the Catholic cardinal’s attorney and tended to legal matters for him across Europe, aided by his shrewd intellect and facility for language. (He spoke English, French, Italian, Spanish, Latin and some ancient Greek.)

After Wolsey died in 1530, the English king was impressed with Cromwell’s loyalty, canniness and ability to get things done. Henry VIII appointed him Chancellor of the Exchequer in 1533, then offered him other prominent positions in succeeding years.

As chief minister, Cromwell was responsible for ending the king’s first marriage so he could wed Boleyn in hopes of having a male heir. Where Wolsey failed to get an annulment from Pope Clement VII, Cromwell succeeded by authoring the Act of Supremacy, making Henry VIII head of the Church of England. That legislation ushered in Britain’s Protestant Reformation, severing ties with the Catholic Church in Rome.

“The Reformation would have come to England anyway, Cromwell just sped it up dramatically,” Angus says.

Not content with a religious revolution, Cromwell also set about to reform government. In Tudor times, administration of state services played out at the whim of the king and a few royal servants. Often, after Parliament passed a law, little was done to follow it up, and public projects were managed on a haphazard basis–if at all. To address the inefficiency, Cromwell pioneered England’s modern form of government by organizing a central base of operations, hiring knowledgeable people to supervise different government functions and instituting proper oversight and record-keeping.

In 1536, Cromwell oversaw the dissolution of Catholic monasteries and convents across the realm. As part of the Reformation, the Crown seized assets of hundreds of abbeys, sold the property and poured that newfound wealth into England’s depleted treasury.

While this lined the pockets of Henry VIII–and enriched Cromwell, too–it also created enemies. Among them was Thomas Howard, Duke of Norfolk, who was forced to move his family burial plot from a shuttered monastery. It later gave Lord Norfolk the motive to attack Cromwell when he was most vulnerable.

That time came following Henry VIII’s wedding to fourth wife Anne of Cleves in 1540. After the 1537 death of Jane Seymour in childbirth, Cromwell arranged this match to strengthen ties with the German duchy. When the king first met Anne, he was so turned off by her appearance that he failed to consummate the marriage, which was annulled six months later. Henry blamed Cromwell for the fiasco, giving the chief minister’s enemies the perfect opportunity to pounce.

Lord Norfolk and the other nobles who resented Cromwell for his low birth spoke out, alleging he was a heretic who had committed treason. On June 10, 1540, Cromwell, newly named the Earl of Essex, was arrested and held in the Tower of London. Without formal charges or a trial by jury, he was beheaded July 28, 1540–the same day the king married his fifth wife, Catherine Howard.

Within weeks, Henry VIII regretted axing his righthand man. He was heard to say “he had put to death the most faithful servant he ever had” and blamed the decision on “false accusations” from his ministers.

Cromwell’s fall from grace happened nearly as quickly as his ascension to power. Perhaps better than anyone else, the commoner who was second only to the king understood that ultimately his misdeeds would come back to haunt him.

“Cromwell knew who he was,” says Angus. “He could accept that ugly things had to happen. He knew the threat. And he knew eventually that threat would close in on him too. He said, ‘Only God can really judge me, and I have to wait for that day.’”