The 1940's were all about structured and sleek garments.
Wide shoulders (shoulder pads) were offset by sculpted hair with not a strand out of place (victory rolls).
Because fabric had to be rationed, finer fabrics were not available to the public so clothing had to be more practical in order to be worn more regularly and to the work place. Things like silk were used for parachutes, and nylon stockings were considered a luxury, so wearing a 1950's petticoat wouldn't even be imaginable during war time.
Because the 40's were so very structured, a simple a-line skirt was cut just below the knee. It was spruced up using pleats and seams to give it the illusion of being fuller. Here's an example of some war time fashion
, these dresses were daytime garments practical enough for the work place.
Evening wear was also sleek but dramatic. The shape of the skirt hugged the hips
, resembling more of a pencil, and the hem was brought lower so that dresses brushed the floor, for extra drama sometimes a train was also added. They were not flouncy like a circle skirt but very structured and precise. http://www.dressingvintage.com/vinta...rt-Adrian.html
So really it depends on what you want to do, a circle skirt will not give it the historical silhouette, but to anyone else, it would look like a vintage inspired dress. I hoped this helped some!