"The pen is mightier than the sword" means a person can cause people
to change their opinions(e.g., to fight
on a large scale whereas a sword can only change a peron's opion by force and then
often only results in the person's death.
The Founding Fathers of the United States
of America considered the pen to be mightier than the sword, and therefore were able
of America by uniting the colonists.