Old Style and New Style Dates - Possible Date Conflicts

Possible Date Conflicts

Occasionally using different calendars has caused confusion between contemporaries. For example, it is related that one of the contributory factors for Napoleon's victory at the Battle of Austerlitz was the confusion between the Russians, who were using the Julian calendar, and the Austrians, who were using the Gregorian calendar, over the date that their forces should combine. However, this tale is not supported in a contemporary account from a major-general of the Austrian army, who tells of a joint advance of the Russian and Austrian forces (in which he himself took part) five days before the battle, and it is explicitly rejected in Goetz's recent book-length study of the battle.

Usually, the mapping of new dates onto old dates with a start of year adjustment works well with little confusion for events which happened before the introduction of the Gregorian Calendar. For example the Battle of Agincourt is universally known to have been fought on 25 October 1415, which is Saint Crispin's Day. But for the period between the first introduction of the Gregorian calendar on 15 October 1582 and its introduction in Britain on 14 September 1752, there can be considerable confusion between events in continental western Europe and in British domains. Events in continental western Europe are usually reported in English language histories as happening under the Gregorian calendar. For example the Battle of Blenheim is always given as 13 August 1704. However confusion occurs when an event affects both. For example William III of England arrived at Brixham in England on 5 November (Julian calendar), after setting sail from the Netherlands on 11 November (Gregorian calendar).

The Battle of the Boyne took place only a few months later in Ireland on 1 July 1690 "Old Style". However, it is commemorated as taking place on 12 July "New Style" by the Orange parades on "The Twelfth", and is an exception to the usual historical method of commemorating events of that period within Great Britain and Ireland by mapping the Julian date directly onto the modern Gregorian calendar (as happens for example with Guy Fawkes Night on 5 November).

Because of the differences, English people and their correspondents often employed two dates, dual dating, more or less automatically, as Benjamin Woolley observed in his biography of Dr John Dee, The Queen's Conjurer. Dee fought unsuccessfully for England to embrace the 1583/4 date set for the change. Woolley wrote because of "the decision, England remained outside the Gregorian system for a further 170 years, communications during that period customarily carrying two dates, one 'O.S.' or Old Style, the other 'N.S.' or New Style." Thomas Jefferson, for example, lived during the time Great Britain, Ireland and the British colonies eventually converted to the Gregorian calendar, so he instructed that his tombstone bear his dates of birth and death in the Old Style and New Style, respectively. At Jefferson's birth the difference would have been eleven days between styles, had the New Style been converted to yet, as is evidenced by his "original" birthday of 2 April and his New Style birthday of 13 April.