This all-ages story deals with facts as they were in 1777, obviously far different from today.
While not condoning drinking, readers must understand the complexity of a world where polluted water risked your life. All town water sources were likely to be polluted due to failure to understand basic causation and transmission of disease.
No blood is spilled in the book. Nothing truly graphic is presented. The only oath is "Good God in Heaven!" Lying is condoned when related to personal safety.
This story contains reference to quasi-official seizure of property becoming confused with thievery. The British are not represented as evil, but as more-or-less pleasant people on a country-wide mission where details and individuals aren't all that meaningful.
While advertising intimates that an individual's interest in Joe is ill-intentioned, that is only something Joe suspects. This may provide and opening to discuss personal interaction with adults and "grooming" versus "being nice."