Joseph Blanchard was born in Dunstable, New Hampshire on February 11, 1704 to Capt. Joseph Blanchard and his wife Abiah Hassell. In 1724 he joined the New Hampshire Militia as a lieutenant and served in Capt. Eleazer Tyng's Company. On September 26, 1728 he married Rebecca Hubbard of Groton, Massachusetts. They had 12 children, including Jonathan Blanchard, a New Hampshire delegate to the Congress of the Confederation in 1784.