April 1, 1916 is known as the missing day in Bulgaria. It was decided by law that after March 31, 1916, April 1 would not follow April 1, but April 14, 1916.
The reason was the adoption of the Gregorian calendar. Bulgaria was an ally of Germany and this required unification of the calendar.
After lively three-day debates in the 17th National Assembly, the law “On the Introduction of the Gregorian Calendar” was adopted on March 14, 1916, Monday. It was promulgated on March 21. The change is described in its article 1 (of six):
„From the first of April, one thousand nine hundred and sixteen, the time in the Kingdom of Bulgaria shall be according to the new style - the Gregorian calendar.
The thirty-first day of March, one thousand nine hundred and sixteen, shall remain the last day counted according to the old calendar, and on the day following it the new one shall immediately enter into force with the date of the fourteenth of April, one thousand nine hundred and sixteen, as the beginning of the new time in the Kingdom."
A paradox shines at the very beginning - the legislator was unable to avoid it. He wrote „From the first of April" 1916 and thus referred to a date that will never exist.
It is important to know that although Bulgaria officially adopted the Gregorian calendar in 1916, the Orthodox Church in the country continued to follow the Julian calendar until 1968, when it switched to the so-called "corrected Julian" calendar with a special "Message to the Clergy and All the Children of the Bulgarian Orthodox Church" No. 5953. From that moment on, church holidays are celebrated according to the new style, and movable holidays, such as the Resurrection of Christ and the holidays associated with it, are calculated according to the Julian calendar, i.e. according to the old style.