This article is from the Calendars FAQ, by Claus Tondering firstname.lastname@example.org with numerous contributions by others.
For the man in the street, yes. When Julius Caesar introduced his
calendar in 45 BC, he made 1 January the start of the year, and it was
always the date on which the Solar Number and the Golden Number (see
section 2.12.3) were incremented.
However, the church didn't like the wild parties that took place at
the start of the new year, and in AD 567 the council of Tours declared
that having the year start on 1 January was an ancient mistake that
should be abolished.
Through the middle ages various New Year dates were used. If an
ancient document refers to year X, it may mean any of 7 different
periods in our present system:
- 1 Mar X to 28/29 Feb X+1
- 1 Jan X to 31 Dec X
- 1 Jan X-1 to 31 Dec X-1
- 25 Mar X-1 to 24 Mar X
- 25 Mar X to 24 Mar X+1
- Saturday before Easter X to Friday before Easter X+1
- 25 Dec X-1 to 24 Dec X
Choosing the right interpretation of a year number is difficult, so
much more as one country might use different systems for religious and
The Byzantine Empire used a year starting on 1 Sep, but they didn't
count years since the birth of Christ, instead they counted years
since the creation of the world which they dated to 1 September 5509 BC.
Since about 1600 most countries have used 1 January as the first day
of the year. Italy and England, however, did not make 1 January official
until around 1750.
In England (but not Scotland) three different years were used:
- The historical year, which started on 1 January.
- The liturgical year, which started on the first Sunday in advent.
- The civil year, which
from the 7th to the 12th century started on 25 December,
from the 12th century until 1751 started on 25 March,
from 1752 started on 1 January.