In the Medieval times, the thought of a woman riding a horse was considered extremely vulgar. Not only was it frowned upon, it was also very difficult for a woman to try to ride with the long skirts and dresses. Sitting sideways was a good solution and it still preserved the ladies modesty. The side saddle was designed and since then it has evolved over the centuries, becoming easier to use and safer.
The opinion of it being indecent for ladies to ride astride, can be traced back to 1382. The side saddle opened up a new world of freedom for women in these times. Although it solved a lot, the side saddle had to be tweaked a lot along the years. The first side saddle ever made, had no setup to secure or hold the legs in place. It was constructed in a chair like position and the woman would sit sideways with her feet on a footrest. This design was very uncomfortable and unsafe. In the 16th Century, a woman named Catherine de Medici developed a more practical design. She made it to where you would place your right leg over the pommel of the saddle and this allowed more control and safety. In the 1830's, a second pommel was added to the side saddle and it was considered revolutionary. This increased security and more freedom in movement while riding. Women were now able to gallop and jump all while remaining modest.
The most common ladies you would see riding where those of higher class. In the 1850's, riding and dancing were the only activities that were socially acceptable for women of the upper class and aristocracy.
In the Victorian Era, the posture of the side saddle was very similar to the way it is done today. The right leg is placed on the front of the saddle, the left leg is bent and resting on the saddle, and the foot goes in the slipper stirrup. In the 16th Century a specific style of clothing was designed to ride side saddle. Before, women just wore day wear. The first "safety skirt" was invented in 1875 to prevent accidents. It was very common for women riding to get their skirts caught and then get dragged by the horse when they fell off. These safety skirts buttoned along the seams and later developed into an apron skirt that buttoned around the waist, just covering the legs which were encased in breeches.
In the early 20th Century, it became socially acceptable for women to ride astride while wearing split skirts or breeches. This is when the side saddles started to fall out of fashion. Riding side saddle was a symbol of male domination basically. Around 1930, riding astride had become totally acceptable and it was preferred by women. By this time, women were gaining more rights and freedom, including on the back of a horse.
During the last few years, there has been a revival in the art of riding side saddle. It has become a popular new interest among women riders today. Woman now compete, show, or even pleasure ride in side saddles.
(picture credit: https://truewestmagazine.com/the-scandalous-saddle/)