If you have studied another martial art, then it is probably quite difficult to imagine how tai chi chuan can be used effectively in combat. The slow-motion movements lead people to doubt the art.
The Yang style of tai chi chuan was developed by a kung fu master called Yang Lu-chan.
Yang Lu-chan rose to fame in China by teaching his tai chi chuan to the Manchu Emperor's elite palace guards.
His nickname was 'Yang-the-Invincible'.