Berthold descended from the Lower Saxon Landsberg family. His father was Ulrich of Landsberg. He studied Law and obtained his JD degree. He became a canon in Verden and became a dean in 1464. From 1468, he administered the bishopric on behalf of Bishop John III of Asel, who suffered from ill health. In 1470, the cathedral chapter urged John III to abdicate and elected Berthold as his successor. His election was confirmed by Pope Paul II.
In 1472, Berthold and the city of Hildesheim support the candidacy of his cousin Henning of Hus as the next bishop of Hildesheim, against several other candidates. A feud ensued. Henning was unable to prevail against the provost and the local nobility. After another was with Brunswick and Hesse, he withdrew his candidacy in favour if Berthold. Berthold's appointment was confirmed by the pope and the pope also gave Berthold permission to continue to administer Verden.
Great feud
He tried to the financial problems of his bishopric with new taxes. In 1484, this led to a serious conflict with the city of Hildesheim, known as the "Great Feud". The citizens of Hildesheim even went so far as to take some of their bishop's vassals prisoner. Berthold countered with ecclesiastical punishments, such as anathema and interdict. Nevertheless, the city prevailed. As a result, the citizens began to strengthen the city's fortifications. Berthold ordered the city to revert the city wall to their previous size, but the city refused. War broke out again, with both sides plundering and looting the enemy's territory. In 1486, their differences were settled and a peace treaty was agreed. Nevertheless, tensions remained.
Foreign and domestic policies
Berthold concluded a treaty of alliance for a twenty-year period with Duke William I of Brunswick-Wolfenbüttel, who had been his predecessor's greatest enemy. However, it soon became clear that William would not support him in his conflicts with the local nobility. Several North German cities concluded an alliance against their princes; Hildesheim was among them. In 1483, the cities of Brunswick and Hildesheim defeated Duke Henry VII of Brunswick-Lüneburg at Bleckenstedt in 1483. In 1488, Berthold travelled to Rome to object to an unjustified papal ban against the bishoprics of Verden and Hildesheim. He never managed to get the local nobility under control. In 1500, a nobleman from the Schwichelt family convinced the pope to pronounce a ban against the church in Hildesheim again. In 1493, he concluded an alliance for a twenty-year period with archbishop Henry II of Bremen. However, Henry's successor John III cancelled this alliance.
