From "The Island of Second Sight"

Found Thelen's Quixotic book via Celan. An excerpt:

     In the summer of the year 1601, Archduke Albrecht of Austria, the Spanish viceroy in the Netherlands, took up the siege of the city of Ostende. Isabella, who as daughter of Philip II of Spain had presented the Netherlands to her consort Albrecht as a dowry, vowed never to changer her chemise until the city had surrendered to the Spanish army. Albrecht's incentive to bring the siege to a rapid and victorious end was therefore very great, but the princess had underestimated the power of the Ostenders to hold out. The siege ended on the 20th of September, 1604 A.D., with a Spanish victory. Princess Isabella had thus worn her blouse for more than three years, offering proof of her patriotism and moral rectitude. There were solemn fanfares as she publicly dipped her blouse in a washtub. It turned the suds an inky color that today bears her name: a brownish-whitish-yellow tint like café-au-lait, known as "Isabella."

     Surely no one will doubt the truth of this traditional account, insofar as the precise coloration is concerned. I myself regard the background circumstances also as authentic. Who might ever have profited f rom inventing such a story? Or perhaps "legend corrects history," as Pascoaes says. I can only agree with him.

     Historical authenticity on the one hand, with its dry and rarefied scholarly mission, or on the other hand, legend as leaven for poetic truth: both impulses have combined most effectively here to help describe -- but my reader will have guessed what I was getting at -- Zwingli's shirt. It was "Isabella" shade from top to bottom, save for blackish areas on collar and underarms. Had Zwingli, too, taken a vow? Had he pledge himself to someone in eternal grubbiness? Was he besieging something or someone, or was he perhaps himself under a state of siege? The subsequent course of events will provide historical answers to all these questions.