On this day in 1616 – (400 years ago) – the Roman Catholic Church solemnly declared that the works of the Polish astronomer and mathematician Nicolaus Copernicus, who had died seventy-three years earlier, were to be withdrawn from circulation and placed on the index of forbidden books. Expecting this kind of trouble, Copernicus had put off publishing his great work On the Revolutions of the Celestial Spheres until he was on his deathbed. The book not only argued that Aristotle and the Bible were wrong in claiming that the sun revolved around the earth—but showed that actually, the reverse was true. Copernicus had been denounced as a “fool” by Martin Luther and other theologians, but in the years since his death, support for his work had steadily grown among astronomers all across Europe. By banning it, the Catholic Church managed to push it underground for more than a century, but its overwhelming acceptance by scientists finally forced Pope Benedict XV to reverse the ban in 1758.
On this day in 1770 – (246 years ago) – amid growing colonial unrest in Boston, Massachusetts, an argument in the street between a wigmaker’s apprentice and a uniformed British guard quickly escalated into a mob scene in which eight British soldiers were surrounded by more than three hundred angry colonists yelling, spitting, and throwing things at them. In the confusion, the British soldiers opened fire on the crowd, killing five people and injuring a half-dozen others. News of the incident, which became known as the Boston Massacre, quickly spread throughout the American colonies and was a significant factor leading to the Revolutionary War five years later.
On this day in 1940 – (76 years ago) – during World War II, six members of the Soviet Politburo, including Joseph Stalin himself, signed a secret order for the execution of 25,700 members of the Polish military, police, and technical elite, taken prisoner during the recent Soviet invasion of Poland, who were now being held at prison camps in Ukraine and Belarus. Fearing that so many talented people in any future Polish state might create a major threat on the Soviet Union’s western border, Stalin wanted them dead. The methodical executions, known collectively as the Katyn Forest Massacre, took place throughout April and May, sending some 22,000 people into mass graves. Fragmentary evidence of the atrocity was seized upon by Nazi German propagandists, who used it to discredit their Soviet enemy. But the full story was not revealed to the world until the 1990s.
On this day in 1989 – (27 years ago) – in Lhasa, the capital of Tibet, Chinese police fired on a crowd of Tibetan pro-independence demonstrators, sparking riots that continued for three days and ended with the imposition of martial law and expulsion of foreigners from the city. Chinese authorities later claimed that the Tibetan protesters had fired at the police first, but a few dozen Western and Japanese tourists who witnessed the riots later told journalists that at no point had they seen any Tibetan holding a gun. According to Chinese sources, three people died. But the Tibetan opposition put the death toll closer to thirty.