The 17th Century!!!

In the 18th century a new corseted look had over-the-shoulder straps,

was lengthy, and was worn over a blouse. It's supports consisted of

primarily whalebone. During era introduced cotton as the most popular

fabric. Softer more natural lines were fashionable, so most women

divested themselves of the constrictive stays. However, if a woman

didn't have flattering curves, she was still wont to use binds

strategically.

In the 1800's the corset changed  by leaps and bounds. During the

Napoleonic Wars, a doctor with the French army invented a metallic

eyelet. Eyelets was then added to corsets helped them to be cinched

even tighter with no fear of damaging the fabric. When the quality of

the eyelets went under investigation , the Minet Back made its

appearance. The back closure consisted of a series of loops on each

side. A whalebone bar was then passed through the loops. In addition

lacings was threaded through the loops as well which meant that the

pressure for supporting the garment was on the bar instead of

individual points.

                                                                                Whalebone Corset