The year 1665 was one of the most consequential in European history, shaped by a devastating plague that killed over 100,000 Londoners, groundbreaking scientific discoveries, a major naval battle, and the birth of scientific publishing. Several of these events were directly connected: the same plague that emptied London’s streets also sent a young Isaac Newton home from Cambridge, where he began work that would reshape physics and mathematics.
The Great Plague of London
The defining event of 1665 was the Great Plague, the last major outbreak of bubonic plague in England. London lost roughly 15% of its population. Official records counted 68,596 deaths, but the true number was probably over 100,000, since many deaths went unrecorded, particularly among the poor. The disease spread through flea bites carried by rats, though people at the time didn’t understand the mechanism. Wealthy residents, including King Charles II and his court, fled the city. Those who remained faced quarantine orders, with infected households marked by a red cross on the door and the words “Lord have mercy upon us.”
The plague wasn’t confined to London. In the Derbyshire village of Eyam, an outbreak began in September 1665 after infected fleas arrived in a shipment of cloth from London. Under the guidance of the local rector, William Mompesson, the villagers made a remarkable decision: they quarantined themselves to prevent the disease from spreading to surrounding communities. Over the next 14 months, 257 of Eyam’s roughly 700 residents died, a mortality rate of 37%. Mompesson recorded every victim’s name and burial date in the parish register. Entire families were wiped out, but the self-imposed quarantine likely saved the wider region from a far worse outbreak.
Newton’s “Year of Wonders”
When plague swept through Cambridgeshire, the University of Cambridge closed its doors. A 22-year-old Isaac Newton returned to Woolsthorpe Manor, the modest Lincolnshire farmhouse where he had grown up. What followed is sometimes called his “annus mirabilis,” or year of wonders. Working largely alone in 1665 and 1666, Newton laid the foundations for three ideas that would transform science: an early version of calculus, his laws of motion, and the theory of universal gravitation.
At Woolsthorpe, Newton also conducted experiments in optics, using prisms in his bedroom to investigate the properties of light and color. He demonstrated that white light is composed of a spectrum of colors, a finding that contradicted centuries of assumptions. And it was here, according to Newton’s own later account, that a falling apple in the orchard prompted his thinking about gravity. Whether the apple story is literally true or a simplified retelling, the work Newton began during the plague years fundamentally changed how people understood the physical world.
Robert Hooke and the Discovery of Cells
In 1665, the English scientist Robert Hooke published “Micrographia,” a landmark book of observations made through a microscope. Among its many illustrations and descriptions, one stood out: Hooke had sliced a thin piece of cork and examined it under magnification. He saw a honeycomb-like pattern of tiny, repeating boxes. He called them “cells,” borrowing the Latin word “cellula,” which referred to the small rooms inhabited by monks. Hooke didn’t realize he was looking at the fundamental structural units of all living things, but his term stuck. The word “cell” in biology traces directly to his 1665 observation of cork bark.
Hooke did more than glance at a single slice. He developed indirect illumination techniques and studied sections cut in multiple planes to reconstruct the three-dimensional structure of plant materials. “Micrographia” also included detailed drawings of insects, fabric fibers, and other specimens, opening a previously invisible world to public attention and inspiring a generation of microscope users.
The First Scientific Journal
On March 6, 1665, the first issue of “Philosophical Transactions” was published under the editorship of Henry Oldenburg, who also served as Secretary of the Royal Society. It was the world’s first scientific journal. The early issues compiled edited portions of Oldenburg’s correspondence with researchers across Europe, reviews of recently published books, and accounts of experiments and observations from natural philosophers in Britain and the continent. The journal’s purpose was straightforward: to inform the Fellows of the Royal Society and other interested readers of the latest scientific discoveries. That basic model of peer-driven scientific communication, born in 1665, remains the foundation of how research is shared today.
The Battle of Lowestoft
The year 1665 also saw the first major naval engagement of the Second Anglo-Dutch War. On June 13, an English fleet of about 100 ships under the command of James Stuart, Duke of York (the future King James II), met 107 Dutch ships led by Jacob van Wassenaer, Baron Obdam, off the coast of Lowestoft in Suffolk. The battle was a decisive English victory. The Dutch lost 17 ships (9 captured, 8 sunk), while England lost only one, the Charity. Baron Obdam was killed when his flagship exploded during the fighting. The victory gave England temporary control of the North Sea, though the Dutch would recover and the war would continue for two more years.
The Five Mile Act
England’s religious tensions produced new legislation in 1665. Parliament passed the Five Mile Act (formally the Nonconformists Act 1665), which targeted Protestant ministers who refused to conform to the practices of the Church of England. Under the law, nonconformist clergy were banned from coming within five miles of any city, town, or parish where they had previously preached, unless they swore an oath of loyalty and nonresistance to the Crown. Violators faced a fine of forty pounds, a substantial sum. The act also barred nonconformists from teaching in public or private schools. It was part of a broader set of laws known as the Clarendon Code, which collectively aimed to suppress religious dissent and consolidate the Church of England’s authority after the upheaval of the English Civil War and the Restoration.
The Kangxi Emperor’s Early Reign
Outside Europe, 1665 fell during the early years of the Kangxi Emperor’s reign in China. Kangxi had ascended the Qing dynasty throne in 1661 at the age of seven, and in 1665 he was still a child ruler with regents governing on his behalf. He would not take personal control of the empire until 1669. His reign, which lasted until 1722, became one of the longest and most stable in Chinese history. Kangxi eventually established imperial workshops for the production of court paintings and decorative arts, expanded the empire’s borders, and presided over a period of cultural and economic prosperity. In 1665, however, that legacy was still ahead of him, and the Qing dynasty was still consolidating its power after overthrowing the Ming dynasty two decades earlier.