# Explain this holiday calendar oddity

Happy Boxing Day! Yesterday was Christmas Day, and in a few days, it will be New Year's Day. Each holiday season, those two holidays are always on the same day of the week (in this case, Friday). But in 1914, Christmas Day and New Year's Day were on different days of the week. Why?

• Given the 'real' tag, I can only imagine this has something to do with the Christmas truce of 1914. However, that did not change the day of the week on which Christmas occured (which was a Friday, by the way). Dec 26 '20 at 13:59

• Va snpg, jr xabj gurl ner abg gur fnzr qnl, orpnhfr $12/25/14$ naq $1/1/15$ ner ba gur fnzr qnl, fb $1/1/14$ vf gur qnl orsber. Gurer vf abguvat fcrpvny nobhg 1914 urer, gubhtu. Dec 26 '20 at 20:32