(Chapter 5) Footnote 30:

Vesalius would have known Pfluegel in 1536-37, when Vesalius was completing his baccalaureate at Louvain. This fulsome tribute reflects the excitement of hearing of the successful defense of Louvain against the invading French in July 1542, and his friend’s role (here somewhat exaggerated — the commander was a Portuguese nobleman, Damiau de Goes) in that defense. It is also an oblique tribute to Vesalius’ future employer Charles V, whose territories in the Low Countries were under attack by Francis I of France. The addition of this ending to Chapter 5 is taken as evidence that Vesalius did not send the manuscript of the Fabrica to the printer in pieces as they were completed, but sent in the entire work, complete with later interpolations, no sooner than August 1542. See O’Malley pp. 123, 188. The reference to Pfluegel and his exploits was deleted from the 1555 edition.