We had an odd situation crop up in our last game. Austrian player was advancing a 3 battalion brigade in a column of lines against 2 Prussian battalions with artillery. What with heavy fire on themthe whole brigade was roughed up and the lead battalion was brought up to 4 hits and had to retreat through the 2nd unit, giving it a hit (bringing it to 2) and with no room to stop there had to pass through the 3rd unit which already had 3 hits. Also note the lack of maneuver room to avoid the supports. After assigning the pass through hit, unit 3 now has 4 hits and has to retreat through the already moved 1st unit giving it ANOTHER hit taking it to 5 and done for.
Austrian player was somewhat miffed at this but took the reading of the rule with good graces. I on the other hand (being the Prussian) felt a little guilty at this, seemingly cheesy way to eliminate his unit... after all they were grenadiers and all.
So, did I read the rule correctly or do I owe him an apology before the next game?
If the 3rd unit gets passed through by 2 retreating units then it has to take 2 hits. Note the top of p.30 - interpenetrated units forced to retreat follow the unit that interpenetrated them. So if I have it right the 3rd unit in your example doesn't have to pass through unit 1 - it can follow it, with unit 1 extending its retreat as required. Therefore it should end up with 4 hits rather than 5.
I think the Austrian player needs to learn a tactical lesson - don't bunch up your units! Nothing cheesy about attacking units which are not properly spaced getting kicked into touch.
Ahhh… I like that, feels much better. In this case I don't think it would have made a huge difference since there may not have been 15cm behind unit 3 before the table edge… or the artillery was gearing up for bounce through fun! However, I will offer apologies as appropriate. I hope he learned his tactical lesson, although his explanation involved dithering Austrian commanders and lack of sleep coming off of nights at work. I'm really glad we play for fun not glory!
I would have thought that the third battalion would be terrified by seeing some of their comrades-in-arms fleeing from the enemy. This would tend to make them break and flee BEFORE they got interpenetrated. Being further back, they would be able to run further than the first battalion as well. Thus no interpenetration.
You can certainly try playing it that way if you wish. The way the rules function is that it is the interpenetration that actually causes the hits (which may in fact just represent disruption or disorder), and the casualties then trigger a retreat or rout reaction. Thus the interpenetrated unit follows the unit already falling back.