Mounting on the crupper behind one of the officers of the escort, she was then to fly to the frontier, relays of horses having been provided at every stage until she should reach Rocroy, the first pausing place within French territory; a perilous adventure for the young and delicate Princess in a winter of almost unexampled severity.
On the very morning of the day assigned for the adventure, despatches brought by special couriers from the Nuncius and the Spanish ambassador at Paris gave notice of the plot to the Archdukes and to Conde, although up to that moment none knew of it in Brussels.

Albert, having been apprised that many Frenchmen had been arriving during the past few days, and swarming about the hostelries of the city and suburbs, was at once disposed to believe in the story.

When Conde came to him, therefore, with confirmation from his own letters, and demanding a detachment of the body-guard in addition to the burgher militiamen already granted by the magistrates, he made no difficulty granting the request.

It was as if there had been a threatened assault of the city, rather than the attempted elopement of a young lady escorted by a handful of cavaliers.
The courtyard of the Nassau Palace was filled with cavalry sent by the Archduke, while five hundred burgher guards sent by the magistrates were drawn up around the gate.

The noise and uproar, gaining at every moment more mysterious meaning by the darkness of night, soon spread through the city.