I say "sudden" because one afternoon I had no such thing, and by that evening I did, or at least half of one. But there's been much planning and some blogging about this gown upcoming, so it's not so much of a surprise. :-)

This is gown #1 in my wardrobe, for the Jane Austen Festival coming up in July. I've decided to make two dresses, one representing the early end of Jane Austen (the 1790s), and one representing the later end (the 18teens).

My references for this 1790s gown are as follows:
American Duchess Historic Shoes Blog
Kyoto Costume InstituteAmerican Duchess Historic Shoes Blog (AC9123 94-14-1) from 1795. I love the high back. It seems to be particular to the 1790s.
American Duchess Historic Shoes Blog
Kyoto Costume InstituteAmerican Duchess Historic Shoes Blog (AC5793 88-19-22), 1795-1800. Nice wrap-front, loose sleeves, and I like the curved edges of the skirt hem
I particularly liked the atypical high-rise back of the KCI gown (the back view), and also the seemingly simple, gathered front. Also eye-catching are the fairly loose, 3/4 sleeves. All in all these look easy to wear, comfortable, and cool.

I started with a fitted lining on the back, draping in muslin, upon which I endeavored to mount the voile and create decorative pleating, something like on the back of the Tidens Toj gown:

American Duchess Historic Shoes Blog
Draping. I have an extreme rise in the back...might as well make it interesting, right?

American Duchess Historic Shoes Blog
The fitted lining. Three seams.
American Duchess Historic Shoes Blog
Mounting the voile on the back. I added the extra pleaties to look like seams. Cool huh? I sewed these down and cut the excess off.
After the back of the bodice was worked, the rest of the construction sortof just happened organically. I have never worked on the form as much - usually I am the type that must pattern everything on paper first, but this gown has just gone together quite nicely, with fixes made where need be, on the fly.

I did run into some problems, though.

First, the width of the fabric (the direction in which the slightly oblong "dots" of the dotted swiss run) was way too short to form the length of the skirt, so I had a moment of panic hoping I was going to have enough fabric to complete the gown, since I only ordered 4 yards. Luckily it's come out just right with the dots now running horizontal (it's barely noticeable), and I have plenty of length in the skirt.

American Duchess Historic Shoes Blog
This is looking too short...
Problem Two was one I expected. I almost always have to add strap extensions onto historical garments, even ones I pattern myself. My mistake was in not putting my short stays on my mannequin and working over the top, because I did not get the placement of the empire waist correct. Luckily a strap extension fixed this problem and now everything is in its proper place. Strap extensions are historically accurate too , yay!

American Duchess Historic Shoes Blog
A little patch piece for the strap extension - this is the lining, and the voile went over this.
American Duchess Historic Shoes Blog
See? Not bad at all. It looks wide, but this includes allowance for the sleeve heads. Also, the backs of 1790s gowns are not the low scooped backs we see later in the Regency, but instead are quite high, even higher than this, up to the neck.
Now for some details:

This gown is ridiculously simple. The front piece is literally one long rectangle gathered at the top, and with a drawstring under the bust. I removed a small bit of volume to create the curve for the armscye, but that's the only cutting I did.

American Duchess Historic Shoes Blog
One half of the front. Working over the stays made it much easier, and I could get the waist in the right place. That is all one piece of fabric. Side note: these are a pair of Regency stays I made rather a long time ago and I am planning to replace them with some proper 1790s short stays, but the waist should stay the same, although the overall shape of the bust should be much improved, when wearing this.
The skirt in back is one long rectangular piece gathered onto the bodice.

American Duchess Historic Shoes Blog
My progress so far- this is from the back.

The front of this gown *will* need an underbodice. I thought I could get away without one, but I learned that there is unwanted poofage on the side of the bust with the drawstring style, and this needs to be tacked down to the underbodice, to keep everything in place. It will also keep the back laying nicely and tightly.

I still have the second half of the front to sew on, and then the sleeves, but I'm really pleased with how quickly and easily this gown has come together! I can instead spend my time on getting the hair and wrappy headgear correct...and acquiring massively large feathers :-)
American Duchess