In its broadest definition Ost-Friesland can be used to embrace all the Frisian parts of the German state of Lower Saxony, i.e. those areas which represent the "East Section" of the Inter-Frisian Council (which include the former Rüstringen (Butjadingen etc.), Land Wursten and sometimes other areas).
With the assistance of farmers from Stadland and Butjadingen, which had father had conquered in 1514, he managed to gain a large amount of fertile territory by constructing levees around some wetlands in the Jade Bight.
In his effort to become the ruling count John V invaded the Weser and North Sea marshes of Stadland and Butjadingen with mercenaries in April 1499, to both of which the Prince-Archbishopric of Bremen claimed its overlordship, in order to subject their free peasants.
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This was the start of a series of campaigns to subject the free peasants in the North Sea and river marshes to feudalism, to wit Altes Land, Ditmarsh, Land of Hadeln, Haseldorfer Marsch, Kehdingen, and Wilstermarsch, also known as the Elbe Marshes, Butjadingen and Stadland (today's Weser Marsh), as well as Stedingen, the Land of Würden, and the Land of Wursten.
Mellum formed as an island off the end of the Butjadingen peninsula – which divides the outflows into the Wadden Sea of the Jade and Weser rivers – only at the end of the nineteenth century.
The height of this peninsula, comprising Stadland and Butjadingen, lies between 0.8 metres under sea level (NN) and 1.2 metres above it (at a place on the 'neck' of the Jade Bight it reaches 2 metres).