The essential question of “A Plea for Captain John Brown” is when violence is permitted in a civil society. To counter reports that made Brown out to be wild and unstable, and his attack thus unjustified, Thoreau sought to portray Brown as a committed, disciplined man who was faithful to his cause. This apologia is predicated on comparing Brown with revolutionary leaders of the past, and also on presenting Brown as a modern transcendentalist man living by his values. Thoreau’s rhetorical approach is to build up Brown’s moral and rational perspective, and then to contrast this with the daily unremarked violence of slavery. The juxtaposition damns the situation in the US and looks forward to a future beyond slavery when Brown would be regarded as heroic.

Thoreau argues for the validity of anti-government violence by appealing to his Concord audience’s pride in the city’s Revolutionary War history. Thoreau traces Brown’s own ancestry to the Revolutionary War, implying that he has inherited its ideals. Meanwhile, Brown’s Puritan upbringing connects him to English revolutionary Oliver Cromwell, who also employed violence to establish his political goals, deposing and beheading King Charles I to establish a theocratic dictatorship in England.