The Original Isshin-Ryu Karate System by Chris Thomas

A MUST READ article

....In this setting, the art that Shimabukuro was teaching would require two outstanding qualities:
1. It would have to be a straightforward style, which was quickly and easily taught to soldiers;
2. It would have to be absolutely devastating. This is the cauldron in which Isshinryu¹s simple, direct and linear approach was developed.

by Chris Thomas Black Belt Magazine, January 1996