Nov 1

"All Hallow’s Day (November 1st).
The French call it Toussaint, which we have translated All Saints’ Day. Hallowmas is All-Saints’ festival. (Anglo-Saxon, hálig, but Hálig-mónáth was September, and Hálig-dœg was simply a Holy-day.)"

"All Saints
or All Hallows. In 610 the Pope of Rome ordered that the heathen Pantheon should be converted into a Christian church, and dedicated to the honour of all martyrs. The festival of All Saints was first held on May 1st, but in the year 834 it was changed to November 1st. 'Hallows' is from the Anglo-Saxon hálig (holy)."


--E. Cobham Brewer, Dictionary of Phrase and Fable, 1898 edition "Revised, Corrected and Enlarged"