Henry David Thoreau was a leading abolitionist, he openly resisted multiple injustices of the state and the times he had to live in, this behavior cost him his social status and even at one point his freedom.
He was also interested in environmentalism and even questioned several factors of the way of living during those times.
Answer:
Henry began to be louder about the invasion of Mexico and saw a way of protesting in the evation of his taxes. When he was confronted by a tax collector he deliberatly chose jail because of that oposition, he only spent a night in jail since his aunt paid the fee against his will but this experience influenced him so much that he wrote "civil disobedience"