Very well researched first chapter. One of the best I've ever seen.
There's only two minor quibbles I have, and they're both probably the translators fault.
The first are the two rapey soldiers who talk about selling the girl as a slave. Slavery had been extinct in Western Europe since the 1200's (There were other forms of exploitation, and English and Dutch companies were secretly just getting started in the New World). The nearest slave markets at the time were in the Ottoman Empire almost 1000 miles away, too far to make the journey worthwhile. What they were probably talking about was pimping her out to other soldiers in their troop. Renting out her body, not selling into domestic servitude.
The second is the girl, Otto and Heinrich all calling Issak's gun a "rifle" on sight. Rifling existed at the time, and Otto and Heinrich would've probably heard about it at the very least, but it was rare, fussy and tricky technology. None of the three would've recognized the musket as a rile without close examination of the bore first. Again, probably the translators fault.