Willard Dewey was born around 1839, either in Vermont or Massachusetts. By the early 1860s, he was probably living in Kentucky.
He enlisted in the Union army, and he mustered in as a sergeant in the 27th Kentucky Infantry on March 21, 1862. The regiment took part in the Battle of Shiloh, the siege of Corinth, the Battle of Perryville, and the Atlanta campaign. He was reduced to the ranks in April 1862, but he was promoted to quartermaster sergeant in November 1863. He mustered out on March 29, 1865.
He settled in Louisville, Kentucky, after the war, and he earned a living as a blacksmith. He married Mary T. Richardson on May 1, 1872, and they had two children: Sam, born around 1876; and Arthur, born around 1878. They lived in Louisville until around 1887, when they moved to Orlando, Florida. He applied for a federal pension in December 1894 and eventually received one. According to a local writer, he owned “one of the finest orange groves” in the region. He died in Orlando on December 5, 1899.