This medieval game takes place in Northern Germany it would prove useful to have a sense of the geography known as the North German Plain. This is bounded by the coasts of the North Sea and the Baltic Sea to the north and Germany's Central Uplands (die Mittelgebirge) to the south. Poland and the Netherlands bound it to east and west.
The lowest points are low moorlands and old marshland on the edge of the ridge of dry land in the west of Schleswig-Holstein (the Wilster Marsh is 3.5 metres below sea level) and in the north west of Lower Saxony (Freepsum, 2.3 metres below sea level).
The highest points– e.g. on the Fläming Heath (200 metres above sea level) and the Helpt Hills (179 metres).
Bogs were formerly widespread but much of this terrain has now been drained or otherwise superseded.
The coastal areas consist of Holocene lake and river marshes and lagoons, wind-borne sand often formed dunes, which were later fixed by vegetation.
Human intervention caused the emergence of open heath such as the Lüneburg Heath.
The most fertile soils are the young marshes (Auen-Vegen) and the Börde areas (Hildesheim Börde, Magdeburg Börde, with their fertile, loess soils).
The north eastern part of the plain contains a multitude of lakes (e.g. the Mueritz lake in the Mecklenburg Lake Plateau).
The Rhine, Ems, Weser, Elbe and Havel are the most important rivers which drain the North German Lowlands into the North Sea and created woods in their flood plains and folds, e.g. the Spreewald ("Spree Forest").
Climate and vegetation
The North Sea coast and the adjacent coastal areas of the facing East and North Frisian Islands are characterised by a maritime climate.
Special microclimates occur in bogs and heathlands and, for example, in the Altes Land near Hamburg, which is characterised by relatively mild temperatures year round due to the proximity of the North Sea and lower Elbe river, providing excellent conditions for fruit production.
Azonal vegetation complexes of moors, riparian forests, fens and water bodies originally stretched along the rivers Ems, Weser, Elbe, Havel and Spree.
Distinctive salt marshes, tideflats and tidal reed beds in the estuaries existed permanently in the tidal zone of the North Sea coast.
The natural vegetation of the North German Plain is thought to have been forest formed mainly by the dominant species European Beech (Fagetalia).
Possible application to the campaign
The majority of participating entities would have arable as their home terrain with littoral for the Scandinavian lands and forest for Poland, Lithuania and Russia.
A number of North German locations listing arable as home terrain could add littoral. these would most likely be members of the Hanseatic League.
Of the items listed for arable difficult hills should be wooded as would gentle hills.
Coastal roadways may be elevated so as to serve as sea-walls or causeways.
Weather does not play a role in DBA, however campaigning in the winter season was a strategy favoured by the Teutonic Order. Definitely something to consider.
map: North German plain
By Deutschland_topo.jpg: User:Botaurus-stellarisderivative work: Bourrichon (talk) - Deutschland_topo.jpg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10437094