Eric II, Duke of Brunswick-Lüneburg

Landgrave Philip I of Hesse predicted: "All sorts of things will happen inside this marriage after the kissing month ends.

"[1] Two years into the marriage, in 1547, Duke Eric began his rule and reconverted to the Catholic faith, after the Reformation had been introduced to his Duchy in 1542.

"[2] Eric turned to a mistress, Katharina von Weldam, with whom he lived at Calenberg Castle from 1563 and had two children: Wilhelm, Baron of Lysfelt (died young in 1585) and Katharina, Baroness of Lysfelt (1564-1606), who married secretly with Giovanni Andrea Doria, Prince of Melfi.

Sidonie was refused access to the castle, which was also based on the grounds that she had threatened "if she comes into my house, I'll cut the whore's nose off and poke out an eye.

"[3] Sidonie was from 1564 onwards virtually under house arrest and she protested vigorously to her brother and to the Emperor, who sent councils who tried unsuccessfully to compromise with Duke Eric.

On 30 March 1572, Duke Eric assembled some of his advisers, nobles and deputies of the cities of Hannover and Hameln on Landestrost Castle in Neustadt.

Instead of Calenberg castle and the silver Duke Eric had withheld from her, she received, after several settlements, compensation and a pension for life.

Neither marriage produced legitimate issue, and on his death in Pavia, Italy, the principality of Calenberg-Göttingen reverted to his first cousin once-removed Duke Julius, who was Prince of Wolfenbüttel.