webdiplomacy.net

In the rules, if I read them right, an army that was not fighting over a province, should be able to retreat to that province.

This is the 2nd game where this rule fails.. Tyr should retreat to Mun, but can only disband...

https://webdiplomacy.net/map.php?gameID ... Type=large

You misunderstand the rules, that's not how it works.

A unit can retreat to an adjacent vacant province if there was no stand-off there. Since there was one in Munich, the army can't retreat there.

Stand-offs are actually a useful way to protect provinces. I'll try to link an example from our rules.

Apparently it's not in our basic rules explanation, but it's explained on page 17 of the rulebook:

http://www.wizards.com/avalonhill/rules/diplomacy.pdf

So in addition to what I said previously, a unit cannot retreat to the province where the attack came from. Fortunately.