Tai Chi as a Martial Art.
Tai Chi for most people, certainly in the West represents a flowing, beautiful, relaxing movement art form and this is true.
It is also however, one of the ultimate martial arts and any contact with high level teachers will make this clear very quickly.
Chen Tai Chi display the martial applications externally. As well as the slow energy collecting movements, there are also fast releases of internal energy, Fah Jing. Dramatic explosive releases of power requiring the practitioner to be totally relaxed in their body and to have conscious control of their internal energy.
Energy moves down from the dan tian to one of the feet, then back up to the body to the waist, and out by the hand, elbow, shoulder or other foot whichever is transferring the power.
Yang and its derivaive forms of Tai Chi may appear not to be martial, but this isn't true, its simply that they evolved to work in a soft way externally, and powerful way internally. The original Yang forms created by Yang Lu Chan also contained Fah Jing and this is practiced in the Yang Tai Chi of Malaysia.
Yang Chen Fu also practiced Fah Jing hand and foot movements most of his life and only later on softened them, so that the energy release is practiced subtely rather than physically. For the highest level of practitioner it will still be there and physical contact with the opponent may not be required.
Chen Tai Chi also contains the full range of wrestling skills, locks, grasps, throws etc. derived from Kung Fu
The older martial Yang Tai Chi contained aspects of the martial use of acupuncture points, blocking the Qi of the opponent - all very dangerous.
The Yang Tai Chi of Yang Chen Fu seems to have focused more on the self defense aspects, using the other persons power against them. Similiar perhaps in some ways to Aikido.
So all in all Tai Chi is most definitely a martial art for those who wish to develop this aspect, but to achieve any kind of proficiency requires years of practice.
It is important to understand as well that internal power comes from years and year of training and cultivation of ones Qi along with the development of a high capacity for 'fang sung'.
The direct pursuit of 'martial skills' in Tai Chi, might not be the right path, and instead a softer journey following the 'natural way' of the Dao might take one much further in the long term.