Contacting enemy to rear when retreating

As I understand it, provided a unit can retreat at least a millimetre (i.e.provided it is not already in contact with an enemy to its rear or flank for that matter) it can retreat without penalty as far as it can go. Does this result in a contact with the enemy to its rear? Does such contact create a combat? Does the enemy to the rear participate in any follow up combat caused by a pursuit (apart from fatally blocking any further retreat)?

Thanks. This situation arises quite a bit in our games as players seek to use the movement of S and LC to get round the rear of the enemy. As these units may not have an Impetus value (i.e. can't charge/initiate combat) or fire into an existing combat, it seems a good tactic for them.

Well if you retreat and contact the frontage of an enemy Unit a new melee arise (the retreating Unit will be probably attacked on the rear).

If the opponent pursues the retreating Unit also in this case we have a new melee and if the retreating Unit contacts an opponent Unit in the process, then no further retreat will be allowed and the melee, if lost, causes the destruction of the (retreating) Unit.

In other word the opponent the retreating Unit contacts while retreating can block further the retreat or be itself the main opponent of a new melee.