Earliest Stamp With In-Design Date?

What is the earliest postage stamp (worldwide) with an "in-design" date? That is, the year date in which the stamp was made that appears as part of the stamp's design. This would not include dates included for other reasons like "1776".

Thanks!!

I would nominate the US Battleship revenue stamps of 1898. I ruled out the Columbian Expo issues because the date on the series of stamps is 1892 but they were issued in 1893. Revenue stamps worldwide are more likely to have dates than regular issues.

The Canadian Diamond Jubilee series, celebrating the 50th anniversary of Queen Victoria's reign, was issued on June 19, 1897 and displays the dates of 1837 and 1897.

In a close second, the Canadian Imperial Penny Postage stamp showing the world map of the British Commonwealth (issued on December 7, 1898), is dated 1898 and is generally recognized as the first Christmas stamp, although it uses the word "XMAS".

The Spanish post office was quite paranoid when it came to forgeries. So it included the year of issue and validity in the design from the first stamp issued in 1850.

NSK - Thanks! That might be the earliest!

1850 will be hard to beat. But it would be interesting to compare different countries. For instance, as far as I'm aware the UK lags behind Spain to the extent of a century and a half, since no GB stamps included a date except for commemorative purposes until 2003, when Northern Ireland regionals had "©2001" unobtrusively microprinted in parts of the design where it was unlikely to be noticed. But from 2010 onwards, most GB definitives have had the year of issue incorporated in an iridescent overprint for security purposes.

1924 Empire Exhibition? Would that not qualify?

ETA: (Specifically as to the UK, obviously...still 74 years behind Spain.)

Those stamps of 1924 (and 1925) were dated for commemorative purposes, commemorating the year(s) of the exhibition.

(Added later:) There are GB revenue stamps from 1860 onwards that incorporate the date of issue in the design, and these stamps were authorised for postal use from 1883 onwards. But the dates on the stamps have no connection with the date when they became valid for postage, so I don't think they qualify as dated postage stamps.