"Man" is one of the three essential parts of the persona--these being: Man, Methods, and Minutia. What we are referring to here by "Man" is the person inside the uniform (not just men, either; women too). Without putting some effort into understanding the German person--his environment, background, traits, etc., it is impossible to understand the German soldier and portray him!
Some of the elements we are concerned with are: appearance, mannerisms, cultural heritage, and language (probably the most obvious characteristic outside the different uniform when compared with American soldiers).
Our basic concept when implementing things in this area is slightly different than our requirements in other areas. In other areas, the main task is to research the correct detail, and use this new detail as our standard. With the "Man" category, however, many of the "correct" details are easy to find, but literally impossible to implement. For example, the most accurate impression of German soldiers would have the reenactors speaking German like natives, without a foreign accent and in the correct regional dialect for their region. Even though the research material to attain such a goal is readily available, we could not realistically hope to set such a high standard for our members. So, in this area at least, we have to compromise. Our minimum standards then, should be to act and sound like (at least to non-German spectators) genuine Germans.
If you doubt the importance of "staying in character," try thinking about it this way: have you ever gone to an event or a living-history facility which specialized in a period that you were not familiar with--then come away genuinely impressed? What was it that impressed you? It was probably not a minute attention to "material authenticity" because the layman doesn't know what is--and what is not--right. Instead, what probably did impress you was the attempt by these living historians to stay "in character," and help give the feeling that you really were talking with a British "Redcoat," a medieval knight, etc. It is this attempt at "staying in character" that makes these historical figures really "come alive!"
One other thing must be stressed: implementing the items detailed in this section is not easy--"Man" is the hardest facet of the impression to develop. Just keep trying, because it is important and eventually you will get it!