Jonathan Blanchard was born in Rockingham, Vermont on January 19, 1811. He was the eleventh of fifteen children born to Polly (Lovell) and Jonathan Blanchard, Sr. When he was three years old, he heard his brother discuss the recent Battle of Plattsburgh, an engagement of the War of 1812. Blanchard later credited this encounter as an influential moment in the development of his pacifist views. As a child, Blanchard attended public schools and helped on the family farm. When he was fourteen, he took his first job teaching a school. Like his brothers, Blanchard opposed the consumption of alcohol. He published his first article advocating temperance in 1825.