You start in the middle of the map. The first attacks will be coming from east and west. Place your long-range-units in the east to destroy the first invader. In the west should stand: the flagellants, the imperial greatswords and the grudgebringer infantry. Put a level one dispel magic on the grudgebringer infantry and attack the goblin shaman. The other two regiments should lay into the archer-regiment. But be careful, it has got fanatics, so try to hold the losses low.
Meanwhile several gigantic spiders and scorpions are attacking, but they can easily be destroyed by magic or commander Bernhardt. Furthermore two nightgoblin-regiments are coming, but they are not worth to talk about...