FEBRUARY 29th is Leap Day.
It was invented in 45 BC when Julius Caesar replaced the many calendars used throughout the Roman Empire based on the moon's lunar cycles with one unified calendar based on the sun, having 365 days and a "leap" day every 4th year.
This was called the "Julian Calendar."
Caesar also made the beginning of the year January 1st.
Previously, the first month of the year was March.
Remnants of March being the first month can be seen in the Latin names of months September, October, November and December:
"Sept" is Latin for seven;
"Oct" is Latin for eight (ie. octogon=eight sided);
"Nov" is Latin for nine; and
"Dec" is Latin for ten (ie. decimal=divisible by ten).
The old fifth month, Quintilis, was renamed after Julius Caesar, being called "July."
As it only had 30 days, Julius Caesar took a day from the old end of the year, February, and added it to July, giving the month 31 days.
The next emperor, Augustus Caesar, renamed the old sixth month, Sextilis, after himself, calling it "August."
A day from the old end of the year, February, was added to August, giving that month 31 days, and leaving February with only 28 days.
After three centuries and ten major persecutions, the Roman Emperor Constantine recognized the Christian religion.
The most important event in the Christian calendar was Christ's crucifixion as the Passover Lamb on the Jewish Feast of Passover, His being in the grave on the Feast of Unleavened Bread, and his Resurrection of the Feast of First Fruits, or as it was later called, Easter.
The Apostle Paul wrote in First Corinthians 5:7 "For even Christ our Passover is sacrificed for us."
Just as Julius Caesar unified the Roman Empire with the Julian Calendar, Constantine, at the Council of Nicaea in 325 AD, decided to have a unified date to celebrate Easter throughout the Roman Empire.
His insistence that Easter be on a Sunday resulted in Christianity cutting ties from the Jewish method of determining the date of Passover based on the lunar calendar, which traditionally began the evening of 14th day of Nissan.
Constantine set the date of Easter as the first Sunday after the first full moon falling on or after the Spring Equinox.
Tables were compiled with the future dates of Easter, but over time a slight discrepancy became evident.
"Equinox" is a solar calendar term: "equi" = "equal" and "nox" = "night" meaning daytime and night are of equal duration, occurring once in the Spring and once in the Autumn.
In the year 325 AD, Easter was on March 21.
In 567 AD, the Council of Tours returned the beginning of the year back to the ancient beginning of March, as January 1st was associated with pagan Rome.
Differing dates for Easter was a major conflict between the Bishops of the Celtic Christian tradition and Roman Catholic tradition, as Saint Patrick confronted the Druid chieftain King Loigaire (Leary) on the night before Easter, c.433 AD, resulting in a large number of Irish converting.
Finally, at the Synod of Whitby Abbey in 664 AD, King Oswy of Northumbria agreed to have the Celtic Church come under the authority of the Roman Catholic Church.
By 1582, it became clear that the Julian Calendar was inaccurate by about 11 minutes per year, resulting in the calculated tables having the date of Easter ten days ahead of the Spring Equinox and thus further from its origins in the Jewish Passover.
Pope Gregory XIII decided to revise the calendar by eliminating ten days.
He set a leap year for every year divisible by 4, except for years divisible by 100, unless that year is also divisible by 400.
It sounds complicated, but it is so accurate that it is the most internationally used calendar today.
Called the "Gregorian Calendar," it also returned the beginning of the year back to January 1st.
Protestant Europe did not adopt the Catholic Gregorian Calendar for nearly two centuries.
This gave rise to some interesting record keeping.
For example: a ship would leave Protestant England on one date according to the Julian Calendar and arrive in Catholic Europe at an earlier date, as Europe was using the Gregorian Calendar.
Another example is April 23, 1616, the day William Shakespeare died in England. Miguel de Cervantes, author of Man of La Mancha, died the same date in Spain, but when the differences between England's Julian and Spain's Gregorian Calendars are removed, Cervantes actually died ten days before Shakespeare.
England and its colonies waited till 1752 to adopt the Gregorian Calendar, but by that time there was an 11 day discrepancy.
When America finally adjusted its calendar, the day after September 2, 1752 (Old Style), became September 14, 1752 (New Style).
There were reportedly accounts of rioting.
Another interesting event occurred on this day during Christopher Columbus' last voyage.
Driven by storms around the Caribbean Sea, two of Columbus' ships were abandoned and the remaining two were worm-eaten and sinking.
Columbus was shipwrecked on Jamaica.
Indians brought food for a while, but then threatened to become hostile.
Columbus, using his skill as a navigator, predicted that a lunar eclipse would take place on FEBRUARY 29, 1504.
He called the Indian Chiefs to his marooned ship and told them if they did not stay on good terms, he would pray that God would blot out the moon.
When the eclipse began, the Indians shrieked and quickly made peace with Columbus.
Columbus later wrote:
"My hope in the One who created us all sustains me: He is an ever-present help in trouble."