Civil War "Soldier's Letter" Envelope Pictures Showing Various Postage Costs

After writing the post for October 26, 2013 on the Soldier's Letter 3d Maine Envelope, I did a search on the web for other pictures of "Soldier's Letter" envelopes.  Here are a few that I found that show some of the various ways postage costs were indicated:

Examples of envelopes without stamps, marked "Due 3":

United State Christian Commission Envelope
"Soldier's Letter"  Due 3

This envelope has the Soldier's Letter tag hand written with the name of the soldier, a chaplain. 

United States Sanitary Commission Envelope
"Soldier's Letter"  Due 3

This second example does not have the name of the soldier written on it, just the written tag Soldier's Letter, with the additional tag "please forward".  I've seen this sort of request tag in variations of wording written on other Soldier's Letter envelopes.  

Example of Envelope marked Due 6:

U.S. Army Hospital Envelope
Soldier's Letter  Due 6

This third example has the "Due 6" hand written in on it.  There is a name written in under the printed "soldier's letter" line, but it was still evidently penalized.  Why was this letter penalized when it has a name written on it?  Maybe it only has the name of the Chaplain and not that of the soldier.  I'm not sure. 

Example of Envelope with two Three cent stamps:

United States Christian Commission
6 cents postage paid

This fourth cover has only the printed tag, not a hand written one of Soldier's Letter, and no name of the soldier written on it.  The two stamps show six cents was paid to receive the letter.

 
    These examples are not presented as "definitive", but only as "illustrative" and "interesting".  As I said, I pulled these four examples off the web from sites that were selling them, so I do not have additional information to add beyond what we see on the covers.  There was a "standard practice" that was supposed to be followed . . . then real life brought variations.  I hope my grouping them together for you might be helpful in giving you some options to use in building your living history displays.  Any comment or additional information will be appreciated.