Joe,
Excellent. Lesson so far: A Prussian Infantry Regimental commander will invariably have at the very least, a Red Eagle 4th class, Crown Order 3rd Class and a 25 years Long Service Decoration. In Prussian
Rangliste speak this is denoted as follows:
As your guy does not fit this criteria, he had to be Bavarian, Saxon or a Württemberger. You have now successfully identified the primary decoration on his medal bar and with regards to class, most German orders worn on the bar are of the grade of a Knight's Cross 1st or 2nd Class which confusingly can be the 3rd, 4th or 5th Class of an order. A 2nd Class order (usually a commander's grade is worn at the throat and on more formal occasions is accompanied by a breast order. The 1st Class (Grand Cross), usually an even larger variant is also worn at the throat and has an accompanying sash order.
The site you have linked to is very useful and on the 6th page dealing with Saxony it shows the Order of Merit in the class we need albeit with swords.
There is a slight anomaly with this officer's medal bar; all his Saxon Orders and Decorations should be in a row but a non Saxon order precedes his 25 years Long Service Cross. Naughty tailor!! [-X Clue: There is a Prussian Order in there.
Having sorted that out, the next step is to determine his arm of service and that I hope should be relatively painless.
The identifying of the orders can only come with practice. Some are immediately and unmistakenly recognisable such as a Zähringer Lion or an Austro-Hungarian Iron Crown for example. Others can be a bit trickier! You would have got there in the end.
Regards
Glenn