The story is set in an alternative world wherein the Thirteen Colonies, after gaining independence from Britain, did not succeed in creating the United States, but instead developed into separate and mutually hostile nation-states which often fight bitter wars with each other.
This language has a rich literary tradition of which the Pennsylvanians are proud; and they feel suspicious of, and threatened by the hostile English-speaking nations of New York to their north, and Virginia to their south.
In that Pennsylvania, only the Quaker communities still speak English as their native language, and they are therefore recruited by the Pennsylvanian Intelligence Service as spies to infiltrate the territories of neighboring nations.
As it turns out, he had been in several life-threatening situations in previous worlds he visited and thought making a transit in the countryside away from cities would be the best way to avoid getting attention - a logical idea, but completely wrong.
In this world, the piece of countryside was a hotly disputed no-man's land in a war zone, and the very fact of his speaking English caused him to be suspected as an enemy spy.
And there was also a world where the site of Philadelphia was taken by a Medieval Japanese city, inhabited by suspicious, aggressive sword-wielding Samurai (no explanation of the history which led to this).
However, in the alternate history of Flynn's book, in the 1780s George Washington took a personal interest in the Pennamite–Yankee War and in a fatally misguided step placed a unit of the Virginia militia, commanded by himself, as a neutral buffer between Pennamites and Yankees.
The loose structure of the Continental Congress eventually disintegrated, with the Thirteen Colonies going each its own way as full-fledged nation states—except that the Yankees of New England created their own more narrow confederation.
To Pennsylvanians, Wilkes-Barre became a deeply hated enemy capital, created on stolen land which was rightfully Pennsylvania's (reminiscent of the historical conflict between France and Germany over Alsace-Lorraine).
In the 19th century, the British helped Chiefs Tecumseh and Sequoyah create Native American states which, although thinly populated, were able to stand up to European settlers, with the former Thirteen Colonies being disunited, acting at cross-purposes and often going to war with each other.
The story's plot takes place at a Pennsylvanian festung (star fortress) overlooking the no-man's-land of the Wyoming Valley, whose garrison is tensely expecting the storm to burst.
Flynn assumes that in a situation where Pennsylvania became an independent nation-state, distinct from and often fighting with its neighbors, Pennsylvanisch had a chance to become the official and dominant language, which later immigrants learned upon arrival.