After Scania and the other provinces included in his diocese had been ceded to Sweden through the Treaty of Roskilde in 1658, Winstrup pledged loyalty to his new sovereign, Charles X Gustav, and he was ennobled under the name Himmelstierna, a name he never actually used.

When the Swedish authorities eventually decided to start up a university there a few years later, at least part of the initiative lay with a subordinate priest in the diocese, Bernhardus Oelreich, and Winstrup now turned against the idea.

After the University of Lund was officially inaugurated in 1668, Oelreich was appointed the prokansler ("pro-chancellor"), despite the statutes giving this position to the Bishop.

However, before the war she had caused her husband embarrassment and trouble in Sweden because she declared in public that Swedes were dogs and their children shouldn't have access to school scholarships in Scania.

After the battle of Lund on 4 December 1676, the Swedes slowly wrenched back their grip on Scania and at the peace negotiations 1679, Swedish rule was legally re-established.

In a letter from 4 October 1678, Winstrup's wife Dorothea wrote to the Danish district governor (amtmand) Knud Thott to complain that she and her husband were stuck in the bishop's residence (Lundegaard) in the city of Lund, and that everything had been destroyed; the city burnt down (most lately by Danish troops, before that by continuous fighting), their property confiscated, their food taken away, their carriage confiscated, they had nothing and her husband's health was in decline.

"God knows that Calamity has stricken us often during these times of war...my husband's health is very weak and that he should have to experience this in his old age - they have taken all that we need to survive, and then we had this great fire ("storre ilde bran")...".