The Quinquatrus (March 19 through March 23) was named for the fact that it was the fifth day after the Ides (by the Roman method of inclusive counting), but popularly it came to be regarded as a five-day holiday in honor of Mars.
... I am so sorry to do this to you, but this post has been moved to my new website, Pagan Calendar, and can be found in its entirety here: The Quinquatrus
As you explore this site, you may find links to a "page not found" instead of something cool and magickal. For this I apologize. I am very working hard behind the scenes to restore those pages along with a link to their homes on my new website where they can be viewed in full.