In 1752, the British Empire, including its American colonies, undertook a monumental task: to correct centuries of chronological drift by jumping the calendar forward. In an instant, eleven days vanished from the calendar, and Wednesday, September 2, 1752, was immediately followed by Thursday, September 14, 1752. This guide explains why this radical change was necessary and the chaos it created.

The Need for Reform: The Julian Calendar's Fatal Flaw

The Julian Calendar, in use since 45 BCE, had a simple but flawed leap year rule: add one extra day every four years. This made the average Julian year 365.25 days long, which is about 11 minutes and 14 seconds longer than the true solar year. While small, this error accumulated over centuries. By 1752, the Julian calendar was a full 11 days out of sync with the seasons.

The Switch Day: September 2nd to September 14th

The solution was the *Calendar (New Style) Act 1750*, which officially adopted the more accurate Gregorian calendar. To correct the 11-day drift, the Act declared that the day after September 2, 1752, would become September 14, 1752. For genealogists and historians, this means that the dates September 3 through September 13, 1752, simply do not exist in British or American history.

Historical Confusion: Double Dating and Calendar Riots

The transition was chaotic. For decades leading up to the switch, it was common to see "double dates" on documents, such as "February 10, 1750/51," to clarify whether the year was being counted from the old new year (March 25) or the new one (January 1). While tales of widespread "calendar riots" by citizens demanding "give us our eleven days" are likely exaggerated, the change did cause significant confusion regarding birthdays, rent payments, and religious holidays.

Accurately Converting Dates Before 1752

For accurate historical research, it is essential to know whether a date is "Old Style" (Julian) or "New Style" (Gregorian). The Julian Day Number (JDN) system, which is a continuous count of days, is the only way to calculate the true duration between dates that cross this historical divide.