Mesopotamia (Iraq) instituted the concept of celebrating the new year in 2000 BC, celebrated new year around the time of the vernal equinox, in mid-March. The early Roman calendar designated March 1 as the new year. The calendar had just ten months, beginning with March. That the new year once began with the month of March is still reflected in some of the names of the months. September through December, our ninth through twelfth months, were originally positioned as the seventh through tenth months (septem is Latin for “seven,” octo is “eight,” novem is “nine,” and decem is “ten.”)
The first time the new year was celebrated on January 1 was in Rome in 153 BC (In fact, the month of January did not even exist until around 700 BC, when the second king of Rome, Numa Pontilius, added the months of January and February.) The new year was moved from March to January because that was the beginning of the civil year, the month that the two newly elected Roman consuls – the highest officials in the Roman republic – began their one-year tenure. But this new year date was not always strictly and widely observed, and the new year was still sometimes celebrated on March 1.
In 46 BC Julius Caesar extend year to 445 days (annus confusionis). The normal number of 355 days had already been increased by the addition of the ordinary 23 days, inserted after February 23. As many as 67 days, divided into two menses intercalares, were now interposed between November and December. This year thus consisted of 15 months. After this “year of confusion,” the new calendar really started. Since 153 BC, January 1 was the day new consuls in Rome took office and Romans had commonly used the name of the two consuls to identify a specific year in question. Thus, by officially making January 1 start the New Year, it simply lined up with the consular year. One proposed reason for this switch is that January is thought by most to have been named after the god of transitions and beginnings, Janus, during the reign of the second King of Rome, Numa Pompilius, who lived from 753–673 BC. Thus, it was naturally enough for the Romans to eventually decide to make the switch. However, whether this is the reason or not is very much up for debate. There is no consensus on the question. After Julius Caesar reformed the calendar in 46 BC as the Julian Calendar and was subsequently murdered, the Roman Senate voted to deify him on 1 January 42 BC, in honor of his life and his institution of the new rationalized calendar. Dates in March, coinciding with the March Equinox, the Solemnity of the Annunciation of Jesus Christ, or other Christian feasts were used throughout the Middle Ages as the first day of the new year, although their calendars nonetheless often continued to display the months in columns running from January to December.
In 567 AD the Council of Tours abolished January 1 as the beginning of the year. At various times and in various places throughout medieval Christian Europe, the new year was celebrated on Dec. 25, the birth of Jesus; March 1; March 25, the Feast of the Annunciation; and Easter.
Among the 7th century pagans of Flanders and the Netherlands, it was the custom to exchange gifts on the first day of the new year. This custom was deplored by Saint Eligius (died 659 or 660), who warned the Flemish and Dutch: “(Do not) make vetulas, [little figures of the Old Woman], little deer or iotticos or set tables [for the house-elf, compare Puck] at night or exchange New Year gifts or supply superfluous drinks [another Yule custom].” However, on the date that European Christians celebrated the New Year, they exchanged Christmas presents because New Years’ Day fell within the twelve days of the Christmas season in the Western Christian liturgical calendar; the custom of exchanging Christmas gifts in a Christian context is traced back to the Biblical Magi who gave gifts to the Child Jesus.
In 1582, the Gregorian calendar reform restored January 1 as New Year’s Day. When the new calendar was put in use, the error accumulated in the 13 centuries since the Council of Nicaea was corrected by a deletion of 10 days. The Julian calendar day Thursday, 4 October 1582 was followed by the first day of the Gregorian calendar, Friday, 15 October 1582 (the cycle of weekdays was not affected), So January 1 is after Winter Solstice 10 days now. Although most Catholic countries adopted the Gregorian calendar almost immediately, it was only gradually adopted among Protestant countries. The British, for example, did not adopt the reformed calendar until 1752. Until then, the British Empire —and their American colonies— still celebrated the new year in March.
Most nations of Western Europe officially adopted 1 January as New Year’s Day somewhat before they adopted the Gregorian Calendar. In Tudor England, New Years Day, along with Christmas Day and Twelfth Night, was celebrated as one of three main festivities among the twelve days of Christmastide. There, until the adoption of the Gregorian Calendar in 1752, the first day of the new year was the Western Christian Feast of the Annunciation, on 25 March, also called “Lady Day“. Dates predicated on the year beginning on 25 March became known as Annunciation Style dates, while dates of the Gregorian Calendar commencing on 1 January were distinguished as Circumcision Style dates, because this was the date of the Feast of the Circumcision, the observed memorial of the eighth day of Jesus Christ‘s life after his birth, counted from the latter’s observation on Christmas, 25 December. Pope Gregory christened 1 January as the beginning of the new year according to his reform of the Catholic Liturgical Calendar.