Reinforcing armies

[LorDBulA]

Majestic7 I think You are taking wrong approach to Your problem.
Long logistic lines always where a problem and they are ment to be a problem in EB.

What was already told is the best solution in my opinion.
Reinforce Your troops and dont march them back and forth.
Did Alexander turned back to Macedon to retrain troops? No he trained them in Macedonia and send them to the front.
Marching units back is only reserved for my best units with big experience, if situation allows it (rule of thumb, if they are not silver they are not worth to be send back).
And still theyr place in army is not left empty. Fresh recruits fill in the ranks while veterans are retraining and later veterans are send as reinforcments for the not so fresh recruits ( or used in different army depending on situation ).

But this alone wont solve Your problem. Its great at first but if You go further from Your homeland the problem will return.
Native troops are next step. Usually You can find good replacements for You low to mid level troops ( sometimes locals can be even better then factional troops ).
The trick is to use only the best elite units from Your homeland and replace low to medium quality units with local troops.
Elite guys die much slower so they will last longer giving You time to bring in reinforcements. Light troops die easy so they must be replaced locally.

The last line of defence against attrition are mercenaries. This guys are proffesionals, good quality troops.
If You are still waiting for reinforcements, cant hire quality troops local, go mercenary.

Playing like this can give You much satisfaction when reinforcements reach the front line in right moment, although You had to foreseen the need for them 4 years earlier to have time to train them and then march them to the front line ( i usually dont send single units since this would be micromanagement nightmare ).

Also its fun to watch how Your army composition changes especially if You are expanding in different directions.