Sometimes a retire result calls for two full moves back as outlined under die roll 5 on the break test QRS. This allows it to reach a tenable position.
So what to do in this example? A unit is 8" in front of a stream or others obstacle. The retire result requires it to go back 12". As there is not enough movement to cross the obstacle with an extra 6" does it stop at the edge of the creek as a tenable position or does it make a second full move to cross it? The rulebook says a retire move is a normal move in all respects. In this example a normal move would be to stop at the creek. But does the retire result require a full move and thus two moves in this case?

