The Julian calendar came into use about 1752 in most western countries.
That is not at all true. Such a statement reflects the peculiar view that Britain and the British empire should be what you have called "most western countries". The Gregorian calendar (and not Julian calendar as already pointed out in my previous post) was adopted by four European Catholic countries on the day specified by the Pope's bull, that is in 1582, these were: Spain and Portugal (and their possessions), Polish-Lithuanian Commonwealth and most of Italy. France, Austria and most of the now Benelux countries followed suit, in 1582-1583. Many protestant countries objected, but most of them did adopt the Gregorian calendar between 1700 and 1701 (Denmark, Norway, Germany).
The British Empire did indeed adopt the Gregorian calendar in 1752.