I don't want anyone to have their expectations raised too high on this, so I will be very honest about this feature. It is strictly limited to specific historical scenarios and circumstance. It is NOT an ability for normal units to invoke at will at this time.
Spoilers....
it plays a role in the Saar Offensive scenarios of DLC 1939, which historically was battlefield where mass minefields had a significant impact on the French attempts to advance in the region.