March forth!

Some humorist I read said that "March 4" is the only date that is a sentence.  I haven't checked all the dates but I think the idea is to consider the date to be "March forth!" instead of "March fourth".  The search software Duckduckgo says "there are approximately 40 calendars in use around the world".  Of course, they have histories, some being in their present form way back and some recently formed or modified.