Command and Control basiclly means the ability of a commander to coordinate the actions of the units under him.
The first problem that faces the reenactor is subordination. At most events there is an overall German commander but at that points the organization stops. At the last Cedars of Lebannon battle the Germans were further broken down into Heer, Luftwaffa and Waffen SS. This was a very good solution becuase it was easy to visually keep track of the groups. If you became seperated from your group it was easy to tell where you needed to go.
If a commander intends to have some control over units in the field some arrangement like this will have to be made. Otherwise he will have to keep track of all the individual units. Remember that historiclly most battalions, companies and platoons are composed of just 3 to 4 sub units. This is to allow easy control and limit the number of things a commander has to deal with.
The next problem is that of the commander. He must stay in control of the groups under him. In the real Army all platoon or company commanders have a staff, an executive officer, sergeant and 2-3 runners. If an army thinks these people are neccesary then we probably need them as well. In the 3rd Infantry (U.S.) in Florida they have almost a full platoon with all the staff positions filled. It was interesting to watch and listen to the interaction between the plt. sgt and the squad leaders. Most of this interaction could be heard from 25-30 meters away. It really added to the feeling that a real American platoon was moving up on my position.
At the Dutch Levee battle a German unit moved up from behind us and coordinated with our unit commader for supporting fire while they assaulted the Americans to our front. All the commands given were in German. Now that added a TON to the feeling of being in a WWII battle.
The typical commander will have to stay in contol using just hand signals. This means once a unit is out of sight it no longer is under the control of the commander and no information is given back to the commander about the situation the unit is facing. This happens all to often especially at large battles. Real armys dealt with this by using radios to report when contact was lost.
This is easily accomplished by use of a CB radio. The trick is to mount it in a case that is the approximate size and shape of an original German Army radio. Replace the speaker with an old headset and your 90% the way there. As yet I have not found a good looking replacement for the mic but I am still looking.
Another possiblility is the use of field phones. Original Heers phones run $50-75 but may or may not be working. If your not up to reworking original phones buy modern ones and put them in a carring bag like the germans used. In a defenseive situation you will be able to set out an outpost and have it actually call in enemy movement. If you have a mortar it can direct fire. The Russians at Cedars of Lebanon set up two outposts with phones and had an 81mm mortar fire on targets called in by the outposts. It made moving around a little more dificult.
And last but not least are hand signals. While it may be tempting to make up a few of your own the origianl Heers hand signals are recorded in several places. The German Squad Handbook listed in the reading list has a long section on them. If original hand signals are used then we should all be able to communicat with only small problems.
Remimber when in doubt SEND A RUNNER!