John Armstrong Jr. was an American military officer and politician born on December 3, 1812, in New York. He served as a general in the Union Army during the American Civil War and played a significant role in various battles, including the Battle of Gettysburg. After the war, Armstrong transitioned into politics, serving as the Commissioner of the General Land Office from 1865 to 1866. He was known for his contributions to land management and policy during a time of significant expansion in the United States. Armstrong passed away on February 22, 1883.