Editing Old Style and New Style dates (section)

==Transposition of historical event dates and possible date conflicts==
[[File:Thomas Jefferson's Grave Site.jpg|right|thumb|[[Thomas Jefferson]]'s tombstone. Written below the [[epitaph]] is "Born April 2. 1743. O.S. Died July 4. 1826."<!-- Punctuation transcribed from image – ignore MOS here -->]]
Usually, the mapping of New Style dates onto Old Style dates with a start-of-year adjustment works well with little confusion for events before the introduction of the Gregorian calendar. For example, the [[Battle of Agincourt]] is well known to have been fought on 25 October 1415, which is [[Saint Crispin's Day]]. However, 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 by using the Gregorian calendar. For example, the [[Battle of Blenheim]] is always given as 13 August 1704. However, confusion occurs when an event involves both. For example, [[William III of England]] arrived at [[Brixham]] in England on 5 November (Julian calendar), after he had set sail from the Netherlands on 11 November (Gregorian calendar) 1688.<ref name="C&J19">{{harvnb|Cheney|Jones|2000|p=19}}.</ref>

The [[Battle of the Boyne]] in Ireland took place a few months later on 1 July 1690 (Julian calendar). That maps to 11 July (Gregorian calendar), conveniently close to the Julian date of the subsequent (and more decisive) [[Battle of Aughrim]] on 12 July 1691 (Julian). The latter battle was commemorated annually throughout the 18th century on 12 July,<ref name=Lenihan>{{cite book |last=Lenihan |first=Pádraig |title=1690 Battle of the Boyne |year=2003 |location=Stroud, Gloucestershire |publisher=Tempus |pages=258–259 |isbn=0-7524-2597-8 }}</ref> following the usual historical convention of commemorating events of that period within Great Britain and Ireland by mapping the Julian date directly onto the modern Gregorian calendar date (as happens, for example, with [[Guy Fawkes Night]] on 5 November). The Battle of the Boyne was commemorated with smaller parades on 1 July. However, both events were combined in the late 18th century,<ref name="Lenihan"/> and continue to be celebrated as "[[The Twelfth]]".

Because of the differences, British writers and their correspondents often employed two dates, a practice called [[dual dating]], more or less automatically. Letters concerning diplomacy and international trade thus sometimes bore both Julian and Gregorian dates to prevent confusion. For example, Sir [[William Boswell]] wrote to Sir [[John Coke]] from [[The Hague]] a letter dated "12/22 Dec. 1635".<ref name="C&J19"/> In his biography of [[John Dee (mathematician)|John Dee]], ''The Queen's Conjurer'', Benjamin Woolley surmises that because Dee fought unsuccessfully for England to embrace the 1583/84 date set for the change, "England remained outside the Gregorian system for a further 170 years, communications during that period customarily carrying two dates".<ref>{{cite web |first=John |last=Baker |url=http://www2.localaccess.com/marlowe/bacon6.htm |title=Why Bacon, Oxford and Other's Weren't Shakespeare |archive-url=https://web.archive.org/web/20050404085408/http://www2.localaccess.com/marlowe/bacon6.htm |archive-date=4 April 2005}}) uses the quote by Benjamin Woolley and cites ''The Queen's Conjurer, The Science and Magic of Dr. John Dee, Adviser to Queen Elizabeth I'', page 173.</ref> In contrast, [[Thomas Jefferson]], who lived while the British Isles and colonies converted to the Gregorian calendar, instructed that his tombstone bear his date of birth by using the Julian calendar (notated O.S. for Old Style) and his date of death by using the Gregorian calendar.<ref>{{cite web |date=June 1995 |url=http://www.monticello.org/site/research-and-collections/old-style|title=Old Style (O.S.)|publisher=monticello.org|access-date=6 May 2017}}</ref> At Jefferson's birth, the difference was eleven days between the Julian and Gregorian calendars and so his birthday of 2 April in the Julian calendar is 13 April in the Gregorian calendar. Similarly, [[George Washington]] is now officially reported as having been born on 22 February 1732, rather than on 11 February 1731/32 (Julian calendar).<ref>{{cite journal|url=http://www.slate.com/id/2134455/|title=What's Benjamin Franklin's Birthday?|first=Daniel|last=Engber|date=18 January 2006|journal=[[Slate (magazine)|Slate]]|access-date=8 February 2013}} (Both Franklin's and Washington's confusing birth dates are clearly explained.)</ref> The philosopher [[Jeremy Bentham]], born on 4 February 1747/8 (Julian calendar), in later life celebrated his birthday on 15 February.<ref>{{cite book |editor-first=Timothy L. S. |editor-last=Sprigge |editor-link=Timothy Sprigge |title=The Correspondence of Jeremy Bentham: Volume I: 1752–76 |location=London |publisher=UCL Press |year=2017 |orig-year=1968 |isbn=978-1-911576-05-1 |page=294 |chapter=Jeremy Bentham to [[Samuel Bentham]], 15 Feb. 1776 |quote=God's-daddikins! it is my birthday – say something pretty to me on the occasion. |url=https://discovery.ucl.ac.uk/id/eprint/1558740/1/The-Correspondence-of-Jeremy-Bentham-Volume-1.pdf }}</ref>

There is some evidence that the calendar change was not easily accepted. Many British people continued to celebrate their holidays "Old Style" well into the 19th century,{{efn|See also [[Little Christmas]].}} a practice that the author Karen Bellenir considered to reveal a deep emotional resistance to calendar reform.<ref>{{cite book |last=Bellenir |first=Karen |title=Religious Holidays and Calendars |publisher=Omnigraphics |year=2004 |location=Detroit |page=33}}</ref>