This work is dedicated to application-oriented research. It examines the potential nullity of agricultural mortgage loan agreements for legal practice, particularly based on case law, as well as the possible enrichment, usage, and damage compensation for already completed transactions, using the loan agreements of the former Braunschweig knightly credit institution/association, Wolfenbüttel, from the years 1962-1987 as an example. The legal opinions prepared in this context can also be applied - at least partially - to the assessment of commercial and consumer loan agreements in general. Additionally, the paper aims to invigorate the field of credit law.