1918This year is noted for the end of the First World War, on the eleventh hour of the eleventh day of the eleventh month, as well as for the Spanish flu pandemic that killed 50–100 million people worldwide. Below, the events of World War I have the "WWI" prefix. January 1918 January – 1918 flu pandemic: The "Spanish flu" (influenza) is first observed in Haskell County, Kansas. January 4 – The Finnish Declaration of Independence is recognized by Soviet Russia, Sweden, Germany and France. January 9 – Battle of Bear Valley: U.
Gregorian calendarThe Gregorian calendar is the calendar used in most parts of the world. It went into effect in October 1582 following the papal bull Inter gravissimas issued by Pope Gregory XIII, which introduced it as a modification of, and replacement for, the Julian calendar. The principal change was to space leap years differently so as to make the average calendar year 365.2425 days long, more closely approximating the 365.2422-day 'tropical' or 'solar' year that is determined by the Earth's revolution around the Sun.
1915Below, the events of World War I have the "WWI" prefix. January 1915 January – British physicist Sir Joseph Larmor publishes his observations on "The Influence of Local Atmospheric Cooling on Astronomical Refraction". January 1 WWI: British Royal Navy battleship HMS Formidable is sunk off Lyme Regis, Dorset, England, by an Imperial German Navy U-boat, with the loss of 547 crew. Battle of Broken Hill: A train ambush near Broken Hill, Australia, is carried out by two men (claiming to be in support of the Ottoman Empire) who are killed, together with four civilians.
Julian calendarThe Julian calendar is a solar calendar of 365 days in every year with an additional leap day every fourth year (without exception). The Julian calendar is still used in parts of the Eastern Orthodox Church and in parts of Oriental Orthodoxy as well as by the Berbers, whereas the Gregorian calendar is used in most parts of the world. This calendar, proposed by Roman consul Julius Caesar in 46 BC, was a reform of the earlier Roman calendar, a largely lunisolar one. It took effect on 1 January 45 BC, by edict.