Fred Calef III wrote:
So, my question is, if Yoshinkan is considered 'pre-war' aikido and aikikai being 'post-war' aikido, why did the aikikai stance evolve from the yoshinkan stance?
I would not suppose that it did , actually. I don't know if the pictures of osensei shows the feet clearly enough to show the feet position but personally, I would be very surprised if osensei's hip and feet position pre-war would be Yoshinkan style. If someone can prove me wrong, please do so.
There is some variations here with some people of the Yamaguchi line of Aikikai aikido positioning feet and hips very similar to what you describe as Yoshinkan kamae. This I strongly believe is an influence from the sword work done in this line of aikido, derived from Kashima Shin Ryu. Nishio sensei, another well-known Aikikai teacher, does not place his feet on a line at all, and often lifts the back heel in a way that is seldom seen in other types of aikido. This is probably an influence from his budo experiences besides aikido (he has lots of it).
Like the examples above, I would suggest that maybe the Yoshinkan kamae has another origin than osensei. I am sure some Yoshinkan practitioners can fill in what budo background Shioda sensei had, besides aikido.
Btw, I have never heard it called "kamae" in Aikikai, although this is a very common budo concept. In Aikikai the word is "hanmi", as far as I've heard.