Biographies often cite November 11, 1744 as the day Abigail Adams (née Smith) was born. This is both true and false. While John Adams was 9, his future spouse was born in Weymouth, Massachusetts to Elizabeth and Reverend William Smith, a Congregationalist minister. Back then, Britain’s American subjects still used the Julian calendar. Originally implemented by Julius Caesar in 46 BCE, it remained standardized throughout Europe for more than 15 centuries. Unfortunately, his calendar was about 11 minutes a year out of sync with the earth’s rotation. This might not seem like a big deal, but over time, it became one: By 1582, the calendar was a full 10 days off course. Obviously, some adjustments were needed.
So, in 1582, Pope Gregory XIII introduced a new calendar—one that was designed to eliminate this growing problem. At his command, ten October days were completely skipped over (October 4 was directly followed by October 15) and measures were taken to make leap years happen less frequently. We still use the Gregorian calendar today.
While Catholic countries converted to it more or less immediately, Britain and her colonies didn’t do so until 1752. At that point, the Julian calendar had become 11 days off schedule. So according to this outdated metric, Abigail Adams was born on November 11, 1744. In contrast, our modern Gregorian calendar tells us that she came into the world on November 22.