How did Jethro compare his father to Abe Lincoln in "Across Five Aprils"?

In the beginning of the book, frustrated with the caution and restraint exercised by both men, Jethro compares his father to Abe Lincoln.  Jethro's sister Mary has recently died as a result of the negligence of Travis Burdow, and when an angry mob organizes to hunt down the young man and hang him for his crime, Jethro's father Matt Creighton intervenes, begging the men "to keep their hands free of further bloodshed".  Even though the victim of Burdow's drunken actions is his own daughter, Matt Creighton is a law-abiding, compassionate man, and he is able to overcome his own anger and grief to uphold the peace as it concerns Mary's killer.

Jethro, fired up by the rhetoric of his brothers and a large number of the townspeople, does not understand his father's stance.  He compares Matt Creighton to Abraham Lincoln, at whom many, in the fervor of the pre-war years, are also frustrated because of his reluctance to involve the country in a civil war.  War, at this point, is a glorious, honorable endeavor which should be quickly undertaken and will be easily won in the minds of Jethro and these others, who are wondering why the President doesn't just "start the great explosion which (some) wanted to get started and have finished before the year was well into the summer".  As time goes on and the reality of war and bloodshed hit home, the wisdom of peace-loving men like Matt Creighton and Abraham Lincoln becomes heartbreakingly evident, but at this point in the novel and in history, they only evoke feelings of anger and impatience (Chapter 1).