To pay for it, Congress in July 1798 imposed $2 million in new taxes on real estate and slaves, apportioned among the states according to the requirements of the Constitution.

Congress had also recently passed the Alien and Sedition Acts, criminalizing dissent and increasing the power of the executive branch under John Adams.

[2] There were very few slaves in Pennsylvania, and the tax was accordingly assessed upon dwelling-houses and land, the value of the houses being determined by the number and size of the windows.

The inquisitorial nature of the proceedings, with assessors riding around and counting windows, aroused strong opposition, and many refused to pay,[2] making the constitutional argument that this tax was not being levied in proportion to population.

Pennsylvania auctioneer John Fries organized meetings, starting in February 1799, to discuss a collective response to the tax.

[2] This was important because the three counties in which the opposition was centered (Bucks, Northampton, and Montgomery) were heavily populated by German immigrants.

In response to this action, President John Adams called out a force of federal troops and local militia.

Adams was prompted by the narrower constitutional definition of treason, and he later added that the rebels were "obscure, miserable Germans, as ignorant of our language as they were of our laws"[10] and were being used by "great men" in the opposition party.