The main idea of Lee’s “Letter to His Son” could be expressed best as
a. belief that the integrity of the Union must be preserved at all costs.
b. determination that the South will not be subdued.
c. despair over a Union that can only be maintained by force.
d. an argument in favor of secession.
The main idea of Lee's "Letter to His Son" could be expressed best as despair over a Union that can only be maintained by force. The correct answer is C.
