William, Earl of Lovelace, stood at his dying wife’s bedside on the thirtieth of August, 1852, and heard the confession that would end their marriage in a single sentence. What Ada told him that day has never been recorded verbatim, but the effect was immediate and absolute. He walked out of the room, and he never came back. In the days that followed, he wrote of the utmost wretchedness of mind, of every cherished conviction of his married life unsettled.

He had been married to the Countess of Lovelace for seventeen years. He would not see her again before she died. Ada had never had a chance at a quiet life, not with a father like hers. She was born Augusta Ada Byron on December 10th, 1815, the only legitimate child of the poet Lord Byron.

Every other child he had fathered was the product of an affair, but being born in wedlock did not spare her from a tragic childhood. Byron’s marriage to Anne Isabella Milbanke—Annabella, as she was called—had surprised everyone. He was an incorrigible scoundrel, famous across Europe for his wild antics, from keeping a bear in his rooms at Cambridge to leading troops in the Greek fight for independence. She was stiff, moral, and deeply versed in science, so much so that Byron mockingly called her the princess of parallelograms.

It was from her mother that Ada would inherit her future predilection for numbers. The pet name could not save the marriage. Byron had assumed his first legitimate child would be a glorious boy to carry on the family name, and when he learned he had a daughter, he made no effort to hide his disappointment. Just a month after Ada’s birth, the couple separated.

Soon after, debts forced Byron to flee England for mainland Europe. He never saw his home shores or his daughter again. Byron claimed to keep Ada on his mind, asking family members to send updates on her well-being, writing of her often in his poetry, and keeping her portrait on his desk for years. These were hollow gestures.

Under English law at the time, Byron could easily have claimed custody of his daughter. He never did. His departure left Annabella bitter and angry. She spread scandalous rumors about him and never hesitated to criticize him in front of their child.

As a result, Ada had no relationship with her father whatsoever. She had never even spoken to him when he died of a violent illness at thirty-six, when Ada was just eight years old. She did not see a portrait of him until she was twenty. Instead, her mother dominated her young life, determined to make sure Ada never followed in her father’s footsteps.

From the time Ada was a small girl, Annabella taught her mathematics and logic, hoping that strict schooling in numbers would suppress her daughter’s imagination. She worried that if Ada were given even a taste of the creative arts, she would succumb to the same madness that had plagued her father. But Annabella was more concerned with preventing Ada from becoming like Byron than with being a mother. In public, she appeared the image of a loving, doting parent.

It was a sham. Behind closed doors, the dark truth came out. Perhaps Ada reminded her too much of the husband she hated. Lady Byron spent as little time as possible with her daughter, though she was aware that if anyone caught wind of her neglect, Ada might be taken away.

Every time Annabella received a letter from her own mother asking about Ada, she gave very specific instructions on the cover: keep all of these letters, in case she ever needed to prove she was a caring mother. Her disdain still showed through. In one letter she referred to Ada as “it”: “I talk to it for your satisfaction, not my own, and shall be very glad when you have it under your own. ”

Ada spent her childhood alone at her mother’s country house while Annabella traveled, watched like a hawk by her mother’s close friends, who were under orders to make sure the girl never displayed any sign of moral deviation.

Ada also suffered from painful illnesses, terrible headaches so severe they made it hard to see. As a teenager she came down with a bout of measles so bad it left her paralyzed. She was confined to bed for almost a year, and even after she recovered, she needed crutches to walk for some time. Her mother’s paranoia was not entirely unfounded.

Ada did have a wild side. At seventeen, she embarked on a secret affair with one of her tutors, and the two planned to elope. When Ada presented herself to the tutor’s family, they immediately recognized her as the infamous daughter of Lord Byron and contacted her mother, who dragged her daughter back home and covered the whole thing up. Destiny had other plans.

On June 5th, 1833, fresh from her failed elopement, the seventeen-year-old Ada made her debut in London high society at a lavish ball, where she encountered a man named Charles Babbage. He was not the most impressive figure at the party. In his early forties and unemployed, he made ends meet by giving public lectures, publishing fairly unremarkable scientific papers, and dipping into the sizable sums he had inherited after the deaths of his father and his wife. Not many people found Babbage interesting.

Ada immediately saw him for what he was: a visionary whose ideas would change the world and her life. In their day, a computer was a human being—someone who did computations. Teams of these human computers would split up a complex problem, write out each aspect by hand, and arrive at the answer through laborious mathematics. It was slow, work-intensive, and inefficient.

Babbage assumed there must be a better way. He and Ada began discussing his difference engine, an intricate machine capable of performing complex calculations. Ada was rapt, and Babbage soon recognized her mathematical genius, calling her his enchantress of numbers. Even so, Ada was in the prime of her life, and the allure of high society kept calling.

She became a regular in the London party scene, earning a reputation as a consummate charmer who loved to dance and was not afraid to speak her mind. Though she had never met Lord Byron, his friends could not help but notice the resemblance—not just in her face, but, as one put it, particularly the mouth. London gossips were desperate to know who the scandalous daughter of Lord Byron would marry. Ada could be extremely secretive, which is how she shocked all of England by suddenly announcing her marriage to William, the eighth Baron King, a wealthy English noble.

She became Lady King, and the couple split their time among three extravagant homes. William was the sort of man her mother would have approved of. By all accounts he was a total gentleman, but rigid and deliberate. Like any good Victorian couple, they set about having children immediately.

They married in 1835, and Ada gave birth in 1836, 1837, and 1839. Soon William became the new Earl of Lovelace, making Ada the Countess of Lovelace—the name that would go down in history. In the early years of her marriage, Ada was too busy to think much about mathematics or Babbage’s machine. But after the birth of her third child, she grew restless.

With the help of a math tutor, she dove back into complex problems and imagined ways they could be applied to the real world. In a letter to Babbage, she wondered whether a mathematical formula could be used to play a card game like solitaire. This kind of thinking was nearly unheard of at the time, but it was exactly the sort of idea that would earn Ada her place in the history books. At one point Babbage suggested that Lovelace translate a paper on the Analytical Engine written by the Italian Luigi Menabrea into English.

She did so, and added notes three times longer than Menabrea’s original work. Of all her notes, note G was the masterpiece. Lovelace understood Babbage’s machine better than almost anyone, and in note G she explained one of its practical uses: she described in perfect detail how to use the Analytical Engine to calculate a sequence of Bernoulli numbers. Simply put, note G was in effect the first computer program ever written, making Ada Lovelace the world’s first computer programmer.

Her translation of Menabrea’s article was by far the best explanation of the concept ever written at the time, and it introduced the idea of the mechanical computer to the world. She even predicted that a computer could be used for applications beyond mathematics, such as composing music. The brilliant work nearly destroyed her friendship with Babbage. After Lovelace had spent countless hours writing and translating, Babbage tried to add a preface that amounted only to complaints about his lack of government support.

Ada objected, and Babbage responded that without the preface, she should not bother publishing the article at all. Furious that her friend would scrap her work over a petty squabble, Lovelace published the paper anyway, without the preface. Their friendship was strained for years. Ada knew her worth, even in a Victorian society where women were not supposed to have aspirations beyond the home.

In a letter to her mother, she spoke of her insatiable, restless energy to create something of substance. She was not humble. She wrote: “I believe myself to possess a most singular combination of qualities exactly fitted to make me preeminently a discoverer of the hidden realities of nature. ”

Lady Byron’s response to her daughter’s happiness was vicious.

At the apex of Lovelace’s career, her mother revealed that Ada’s cousin, Lord Byron’s niece Elizabeth Medora Leigh, was actually his daughter as well—that Byron had fathered a child with his own half-sister. It was a bombshell, and meant to be. In a disturbing twist, Ada was not surprised in the least. She claimed she did not blame her father for being seduced.

Ada Lovelace was no innocent, and mathematics was not the only scandalous pursuit she enjoyed. She indulged in gambling, and it eventually got out of control. She spent over three thousand pounds on horses in the 1840s, then tried to create a mathematical model to game the system and cheat her gambling friends out of their money. The model failed spectacularly.

Ada bet it all and lost. Up to that point she had managed to keep her gambling losses a secret from her husband, but she was now forced to come clean. Perhaps because of this and other proclivities, her mother, still very much meddling in her life, hired a man named William Benjamin Carpenter to tutor Ada’s children and to serve as Ada’s moral instructor. But though Carpenter was supposed to show Lovelace how to be a proper lady, she ended up corrupting him.

He fell head over heels for her brash personality and grew increasingly obsessed, spending all his time with her and always assuring her that, as a married man, his intentions were pure. When his advances became too obvious, Lovelace kicked him out of the house. Her life did not get any simpler. Ada had a strained relationship with her own children, just as she had with her mother.

Her eldest son, Byron, left her to join the Navy but deserted soon after. He never contacted his family again. Lovelace held out hope that her son had traveled to America and was living a good life there. She never learned the truth: after deserting, Byron ended up working in a dingy shipyard in England, where he died unmarried and childless at just twenty-six years old.

Ada was not particularly close with her daughter, Anne, either, though Anne fared better than her brother. Anne moved to the Middle East, where she became one of the world’s best-known breeders of Arabian horses. Only the youngest child, Ralph, stayed close to home and eventually inherited the family title, becoming the second Earl of Lovelace. While Ada had always harbored a strange obsession with her mysterious father, Ralph utterly hated Lord Byron.

In 1905, Ralph published a book about his family’s history in which he wrote: “Lord Byron’s life contained nothing of any interest except what ought not to have been told. ”

Ada would have precious little time with any of her children. In her thirties, the health problems that had plagued her throughout her life returned, and she spent months on end traveling from one doctor to the next in search of a cure. This was Victorian England, and medicine was more of an art than a science.

One of the cures her mother suggested was the mystical practice of mesmerism. Ada tried everything, but her health kept getting worse. She was in terrible pain at all times and was prescribed opiates, a common Victorian remedy, to numb the agony. By the 1850s, her doctors had run out of options and had to accept the truth: Lovelace had uterine cancer, and she was dying.

By 1852 there was nothing anyone could do to save the thirty-six-year-old. In one of her final correspondences, she wrote mournfully: “I begin to understand death, which is going on quietly and gradually every minute and will never be a thing of one particular moment. ”

Though few people know her today, Ada had made some impressive friends in her life, and a few tried to visit her on her deathbed. A couple of months before she gave out, she received a visit from none other than Charles Dickens.

She implored him to read her an account of death from one of his books. But Dickens was one of the rare few who could see her. Lady Byron completely took over in Lovelace’s final months. Ada spent her last days as she had spent her childhood: almost entirely alone.

Her mother had never approved of any of her friends and refused to allow many of them to see her daughter to say goodbye. In the meantime, Lady Byron worked to convince Ada to repent her sinful life and devote herself to God. Perhaps it was these urgings that provoked Ada’s disturbing confession. On August 30th, 1852, Ada called her husband William to her bedside and confessed something to him.

When William heard it, he left and never returned. After stalking out of the room, the Earl of Lovelace wrote: “For the past week, I have been prey to the utmost wretchedness of mind. Every cherished conviction of my married life has been unsettled. ”

According to historians, Ada Lovelace told her husband she had been unfaithful to him throughout their marriage, though the exact words cannot be known.

As for a candidate, she had been close with a man named Andrew Cross for several years, and the pair were strangely secretive about their relationship. As Ada lay dying, one of the few people she demanded to see, despite her mother’s protestations, was Cross. When she finally passed, she left all of her father’s possessions to him. Though her husband had abandoned her and her mother had isolated her, Ada Lovelace hung on for three more agonizing months.

She finally died on November 27th, 1852. Her close friend and long-time correspondent Florence Nightingale later wrote: “They said she could not possibly have lived so long were it not for the tremendous vitality of the brain that would not die. ”

Lovelace was buried in an extremely small ceremony. Neither Charles Babbage, her long-time friend and collaborator, nor her own mother attended.

One of Ada Lovelace’s last requests was to be buried next to Lord Byron, the father she had never met.