 Altogether Diepholz was increased in size by 0.8323 ha (8323sq mi) at Vechta's expense.Near the mouth of the Dadau, the water castle of Cornau, the castle of the district Diepholz as part of the Holy Roman Empire, was located between the Dadau and the Hunte, from where the area was ruled up until the castle in Diepholz was constructed.There was a moat to the west of the castle Cornau, which closed the gap between Dadau and Hunte.