Julian calendar

The Julian calendar is the reckoning of time introduced by Julius Caesar, in which every fourth year is a leap year. During the First World War Russia and most of the Orthodox states still kept to it, while the rest of Europe counted days by the Gregorian calendar. In the 20th century the two calendars were 13 days apart, which is why the same event often has two dates in the sources, and in the Polish lands of the Russian partition the two were given side by side even in official papers.

Where the difference came from

The Julian year is slightly longer than the solar year, so over the centuries the calendar drifted away from the seasons. The reform of Pope Gregory XIII in 1582 removed the surplus: 4 October was followed directly by 15 October, and years ending a century ceased to be leap years unless divisible by 400. Catholic countries, Poland among them, adopted the change at once, Protestant ones with delay, and the Orthodox ones only in the 20th century. Since 1900 was a leap year only in the old reckoning, the difference then grew from 12 to 13 days.

Who kept the old style

In Russia the obstacle was the Orthodox Church, which refused to accept the “Latin” reform. Russia’s allies in the Balkans also counted by the old style. For the Serbs the first Austro-Hungarian invasion began on 30 July, and the Battle of Mojkovac of 6–7 January 1916 fell for the Montenegrins on Christmas Eve and Christmas Day.

Romania entered the war on 27 August 1916, which by its own calendar was 14 August. Bulgaria had switched to the new calendar in the spring of 1916, so when its troops took Tutrakan, in Romanian documents the fortress fell on 24 August.

The Ottoman Empire had its own troubles with time. Besides the Muslim lunar calendar it used for official purposes the Rumi calendar, based on the Julian one but with years counted from the Hijra. In February 1917 its days were brought into line with the Gregorian ones: 15 February was followed directly by 1 March, although the numbering of years remained Ottoman.

Dates on this site

We give all dates according to the Gregorian calendar, and for Russian events before February 1918 we add the Julian date in brackets. Hence the names of the revolutions: the February Revolution was decided on 12 March 1917, when the Petrograd garrison mutinied (27 February by the Russian calendar), and the October Revolution took place on 7 November, that is 25 October old style.

The Bolsheviks changed the calendar by a decree of the Council of People’s Commissars: Wednesday 31 January 1918 was followed by Thursday 14 February. The Church stayed with the old calendar, and the Whites in southern Russia kept to it until the end of the Civil War.

The remaining states changed the calendar after the war: Romania and the Kingdom of Serbs, Croats and Slovenes in 1919, Greece in 1923. Turkey abandoned the Ottoman reckoning of years only under Atatürk.