Irregular Encounters was the second supplement for Five Men in Normandy.
Sales link here
I'll give a bit more of a detailed breakdown as well as illustrate whether it is of help to FiveCore players or not.
The goal of this expansion was to illustrate less common situations and provide fodder for scenario writers in particular. Hence, the focus was a bit less on conventional military actions.
It is also one of the smaller supplements, clocking in at only 8 pages.
Force generation table and a new Motivation table for partisan units in world war 2.
This is pretty specific to the way forces are created for Five Men, though it could be used to generate random partisan units for any skirmish level wargame.
Mission - Night Fight:
I honestly don't know why I didn't think of this one when writing Five Men, but better late than never. This is a new mission to play. Goal is to inflict casualties with extra rules for limiting weapons fire and increasing confusion.
You could use this with FiveCore with no problem at all.
Mission - Relief Effort:
A mission where one side has to rescue some wounded soldiers. This is a very iconic "television" sort of mission that can often get players very involved in the fate of their little toy soldiers.
As above, this works fine in FiveCore as well.
This is suitable for partisan scenarios in particular and basically allows civilians to pitch in to help one side or the other.
Some people are partial to more randomness and would appreciate this.
This can be used with no problem for FiveCore and Five Parsecs games (locals pitching in to help take down a gang or fend off Unity troopers)
Special Character - Scrounger:
This is the character archetype of the soldier who always manages to find just what you need.
The scrounger can boost morale, acquire more grenades and can use enemy weapons during battles.
The special characters are intended for use in Five Men campaign games and might not be all that useful in a FiveCore game.
Intended for WW2 scenarios involving reluctant conscript types, this could be used for many FiveCore scenarios as well.
This is essentially a negative skill system. It is applicable to FiveCore games without any problems.
FYI: This table was reprinted without modification in Five Parsecs From Home.