Stephenson:Neal:Quicksilver:747:A Swiss mathematician named Fatio (Neal Stephenson)

From the Quicksilver Metaweb.

Fatio is a real historical figure. His movements and pastimes, as described in this novel, are generally close to historical fact, though of course the details of his interactions with characters in the book are fictional.

It really happened that a Count Fenil hatched a plot to kidnap William of Orange during one of William's sand-sailing expeditions on the Dutch coast and that the plot was divulged and stopped by Fatio.

However, in real life Fatio put a stop to it simply by warning the Dutch in a timely fashion---not by physically intervening as he does in the novel.