The Cambridge English Dictionary offers two definitions of the term “coincidence”: one being “chance or luck,” and the other being “an occasion when two or more similar things happen at the same time, especially in a way that is unlikely and surprising.”
Both definitions have played out many times during the course of history, which has not always unfolded due to consciously planned decisions. There have been many chance happenings or mistakes that wound up shaping future events. Here is a chronological look at some coincidences that ended up changing the course of history.
- The unearthing of the Rosetta Stone
- The driver of Archduke Franz Ferdinand taking a wrong turn
- The chance discovery of penicillin
- The error that led to the sudden fall of the Berlin Wall
The unearthing of the Rosetta Stone

The Rosetta Stone is an ancient Egyptian slab that is over 2000 years old and was created to honor the coronation of King Ptolemy V. The stone is inscribed with the text of the king's decree, which is written in three different languages, one of them being Egyptian hieroglyphics.
Interest in ancient Egypt was reawakened during the Renaissance, which led to renewed interest in hieroglyphics. But without the means to translate them, it seemed the script might be lost forever. What changed that was the rediscovery of the Rosetta Stone: the multiple languages alongside the hieroglyphics meant linguists could finally begin to break the code by comparing them.
What is also remarkable is that the stone was not found as part of an archaeological search, but by accident. By 1799, Napoleon's troops had invaded Egypt, and in July, they began to build forts near the town of Rashid (also known as Rosetta) as part of their campaign. It was during this fortification that the stone is believed to have been found. The object that finally unlocked the door to translating this ancient writing system was, therefore, ultimately a chance discovery.
The driver of Archduke Franz Ferdinand taking a wrong turn

One of the most infamous examples of a coincidence that changed history concerns the journey taken on June 28, 1914 by the man driving Archduke Franz Ferdinand of Austria during a visit to Sarajevo. The Archduke’s assassination on that day wound up being one of the triggers of the First World War.
During his trip, Franz Ferdinand had actually escaped an assassination attempt earlier the same day, but had chosen to continue his duties, and he and his wife had plans to visit a hospital. However, the driver took a wrong turn during the journey, and the car ended up on a street where a student named Gavrilo Princip happened to be sitting at a nearby café.
Princip then took advantage of this chance encounter and assassinated the couple, which led to the eventual outbreak of war. Had the driver not gone the wrong way, the assassination would not have happened, and future events might have played out very differently.
The chance discovery of penicillin

One of the most important substances in the history of medicine was famously discovered by chance. The discovery of penicillin revolutionized the treatment of infections, many of which had previously been fatal, and is considered one of the most important breakthroughs in the treatment of illness and injury.
But it is remarkable to learn of the coincidental events that led to that discovery. The breakthrough has been credited to the scientist Alexander Fleming, who made an important observation following his return to the lab after a vacation.
In his absence, Fleming noticed that one of his petri dishes had been contaminated by a stray mold, but upon further examination, he realized that this also had inhibited the growth of surrounding bacteria. This was the beginning of a process that would lead to the life-saving development of antibiotics, which would change the lives of millions of people around the world.
The error that led to the sudden fall of the Berlin Wall

The fall of the Berlin Wall, which had long divided the city between East and West Germany, was accelerated by chance due to an error made by an East German spokesman in a media briefing.
During a live press conference, Günter Schabowski mistakenly announced that all travel restrictions on citizens moving between the east and west sides of the wall would be lifted immediately, when the official instruction had actually been that it would only begin the following day and not all at once.
This led to thousands of citizens from both East and West Germany rushing to the checkpoints, the pressure of which led to the opening of the border that same night. Had he not made this chance mistake, things might have taken much longer to change.
