On a summer day in July, 1893 Chicago was sweltering hot. Men were advised to place cabbage leaves under their hats to keep cool. People sought refuge from the heat by riding cable cars back and forth, or escaping to the lakeshore. It was on this day that an act of violence would lead to a step forward not just for one black physician, but for medicine as a whole.

Dr Daniel Hale Williams had already made great strides to advance his career and gain respect in a profession that was unwelcoming to minorities. He began his working life with stints that served as preparatory preludes for his eventual career as a surgeon: first as a shoemaker’s apprentice then as a barber, sewing animal hides and deftly wielding sharp blades against skin. He later studied under Dr. Henry Palmer, a prominent surgeon, and graduated with an M.D. degree in 1883.

Williams began practice in Chicago at a time when there were only three other black physicians in the city. His practice grew as he treated both black and white patients, but he was acutely aware of the prejudice against black patients and physicians.

In 1890, Reverend Louis Reynolds, whose sister Emma was refused admission to nursing schools because she was black, approached Dr. Williams for help. This led to the founding of the Provident Hospital and Nursing Training School in 1891—the first interracial hospital in America.

But it was on July 10th, 1893 that Williams truly rose above his peers of every color. In the midst of the heat, tempers flared in one local saloon and the situation quickly escalated into a brawl. A black laborer named James Cornish got stabbed in the chest and was admitted into nearby Provident Hospital.

At first glance Cornish’s wound seemed superficial — there was no external bleeding or evidence of internal hemorrhaging. The puncture was only an inch long, between the fourth and fifth ribs. But as time passed, Cornish showed signs of shock that indicated a more extensive internal injury. Williams concluded that the heart itself had likely been injured and decided to operate. This was a daring, unorthodox decision for its time. Well into the first decades of the 20th century medical opinion still considered the heart an inviolable organ whose complexities lay beyond the limits of surgical skill.

In fact, most contemporary medical textbooks warned doctors to leave heart wounds alone. Even surgical innovator Thomas Billroth advised, “No surgeon who wished to preserve the respect of his colleagues would ever attempt to suture a wound of the heart.”

No doctor would have faulted Williams for giving his patient an opiate and leaving him to his fate. Williams had little guidance and he faced widespread professional condemnation if he failed.

Even so, he decided to take the risk. He cut into Cornish’s chest and saw that the knife had torn the pericardial sac and superficially lacerated the heart. Since he saw no evidence of hemorrhaging from either the heart or the pericardium, he felt no need to explore further.

However, he concluded that the pericardium needed to be sutured to prevent infection and death. He irrigated the wound, sutured it with fine catgut, and dressed it. During the first 24 hours, Williams monitored Cornish’s condition closely. The patient’s pulse and temperature spiked during that time. But by the fourth day, his pulse and temperature had returned back to almost normal levels.

Three weeks after the operation, Williams operated on Cornish one more time to drain fluid in the pleural cavity, and afterward there were no further complications — the patient lived on for twenty years after the operation. Dr. Daniel Hale Williams consequently became the first black doctor to perform open-heart surgery.

After the historic operation, Williams published the account of the case at the urging of his colleagues in the Medical Record of New York on March 27, 1897. He won renown for this procedure and his operation was widely used as an instructive tool for medical students and doctors for years. With such procedures, Williams and other pioneering colleagues were able to show that cardiac wounds could be successfully repaired, paving the way for the rapid advances in cardiac surgery that followed later in the 20th century.

In December 1895, Williams helped organize the National Medical Association (NMA) — the only national organization open to black physicians at the time. He was selected to serve as its first vice president. Williams remained in active practice in Chicago until he suffered a stroke in 1926. He then moved to Idlewild, Michigan where he lived in retirement until his death in 1931.