This had been one of the earliest towns in Germany to embrace the Reformed religion, and up to the close of the sixteenth century the control of the magistracy had been in the hands of the votaries of that creed.

Subsequently the Catholics had contrived to acquire and keep the municipal ascendency, secretly supported by Archduke Albert, and much oppressing the Protestants with imprisonments, fines, and banishment, until a new revolution which had occurred in the year 1610, and which aroused the wrath of Spinola.
Certainly, according to the ideas of that day, it did not seem unnatural in a city where a very large majority of the population were Protestants that Protestants should have a majority in the town council.

It seemed, however, to those who surrounded the Archduke an outrage which could no longer be tolerated, especially as a garrison of 600 Germans, supposed to have formed part of the States' army, had recently been introduced into the town.

Aachen, lying mostly on an extended plain, had but very slight fortifications, and it was commanded by a neighbouring range of hills.

It had no garrison but the 600 Germans.