Charles V Visiting François I after the Battle of Pavia

There is some dispute about the subject shown here, as the Holy Roman Emperor Charles V was only 25 years old at the battle of Pavia, in 1525. Charles had defeated François and taken him captive to Madrid, where he became ill. Charles visited him, concerned that his prisoner might die before a settlement was reached, but François recovered to sign the treaty in early 1526. The drawing may relate instead to a 19th-century German play about a prince and an astronomer.