Complex sentence: The advance on Kandalaksha slowed and stopped, with the troops of Feige's corps dug in and soon the front stagnated, just as it had in the north, combat being reduced to skirmishing and patrol actions.
Split into simpler sentences: The advance on Kandalaksha slowed and stopped, with the troops of Feige's Corps digging in. Soon the front stagnated, just as it had in the north, combat being reduced to skirmishing and patrol actions.