10 April – The Gregorian Calendar versus the Julian Calendar

On this day in Tudor history, 10th April 1585, Pope Gregory XIII died from a fever. He was succeeded by Pope Sixtus V.

Pope Gregory is known for his reform of the calendar. He introduced what is now called the Gregorian Calendar, or Western or Christian Calendar, replacing the Julian Calendar, which had been used since 45 BC.

But why was this reform needed and how was it done?

Find out more about it, and how England didn't use it until the 18th century, in today's talk.

Also on this day in Tudor history, 10th April 1512, Margaret Tudor, Queen of Scots, gave birth to a little boy who would become King James V of Scotland. Find out more in last year's video:

Also on this day in history:

• 1550 – Edward Seymour, Duke of Somerset, was re-admitted into Edward VI's council.
• 1559 – Death of Sir Rice Mansel, soldier and administrator, at his home in Clerkenwell. He served Henry VIII as Vice-Admiral in 1542, in France and Scotland, and in 1544 as Knight-Marshal. He was also Chamberlain of Chester.
• 1586 – Death of Sir Bernard Drake, sea captain, in Crediton, Devon, from probable typhus. It appears that he caught the disease from Portuguese prisoners whose ships he had captured, which were laden with Brazilian sugar, on his voyage to the West Indies.
• 1588 – Death of Robert Glover, herald, genealogist and antiquary in Elizabeth I's reign. He was buried in St Giles-without-Cripplegate.
• 1605 – Death of John Young, Bishop of Rochester and Vice-Chancellor of the University of Cambridge, at Bromley Palace. He was seventy-one, and was buried at Bromley Church.
• 1635 – Death of Lady Helena Gorges (née Snakenborg), previous married name Parr. Helena was Swedish but came to England in 1564 with her mistress, Princess Cecilia, Margravine of Baden, daughter of Gustav Vasa. She fell in love with William Parr, Marquis of Northampton and brother of Catherine Parr, and so remained in England and joined Elizabeth I's household. Helena married Parr in 1571 after the death of his first wife, Lady Anne Bourchier (Parr had actually been divorced from her since 1551). After Parr died, she married courtier Thomas Gorges and had eight children with him. She was laid to rest in Salisbury Cathedral.

Transcript:

On this day in Tudor history, 10th April 1585, Pope Gregory XIII died from a fever. He was succeeded by Pope Sixtus V.

Pope Gregory is known for his reform of the calendar. He introduced what is now called the Gregorian Calendar, or Western or Christian Calendar, by papal bull on 24th February 1582. This calendar replaced the Julian calendar which had been the official calendar of Europe since 45 BC, when it was invented by Julius Caesar in an attempt to bring order to the chaos caused by priests adding days to the Roman calendar in his empire.

By 1582, the Julian Calendar was behind the solar calendar by 10 days and Pope Gregory wanted to correct this. His reform meant that the calendar would advance by 10 days and included instructions that century years, e.g. 1700 and 1800, would not count as leap years unless they were divisible by 400. It also included a reform of the lunar cycle used by the church to calculate the date of Easter, which was far more accurate than the Julian calendar as it only differed from the solar calendar by 26 seconds, which only adds up to a difference of 1 day every 3,323 years.

The 15th October 1582 was the first day of the Gregorian calendar following the last day of the Julian calendar, 4th October 1582, meaning that the 5th-14th October did not exist in the year 1582 in countries adopting the new calendar. However, many countries ignored the Papal Bull and carried on using the Julian Calendar. England, for example, did not adopt the Gregorian Calendar until 1752, when the British Calendar Act of 1751 meant that people went to sleep on the night of Wednesday 2nd September 1752 but woke up the next day on Thursday 14th September – very confusing!

I can imagine it being very confusing for people like merchants and diplomats who travelled between countries who used different calendars.

It’s also confusing for historians and researchers using archives from different countries after the 1582 change as dates would differ for the same event between English and foreign sources. As historical novelist Kate Emerson points out on her website “English reports on the Spanish Armada of 1588 record events as taking place ten days earlier than Spanish reports do”. Benjamin Woolley in his book on John Dee, The Queen's conjurer, explains that communications during the period between 1582 and 1752, when England did start using the Gregorian calendar, customarily carried “two dates, one 'O.S.' or Old Style, the other 'N.S.' or New Style”. So this double dating and the different dates between countries is something to bear in mind when researching records of different countries between 1582 and 1752, as well as taking into account that the new calendar year started on Lady Day, 25th March, rather than 1st January – oh boy!

A piece of trivia for you. The Orthodox Churches still celebrate Easter according to the Julian Calendar because changing it to the Gregorian Calendar would mean that it would sometimes coincide with the Jewish Passover. I will be celebrating Easter Sunday 2020 on 12th April here in Spain, whereas my son in Russia will be celebrating it on 19th April. Hmmm… perhaps I should celebrate it on both days and have extra Easter eggs!