He was working as a bookkeeper in Logansport, Indiana when he enlisted in the Union Army during the American Civil War.

Baldwin entered the Army in 1862 as a private assigned to the 19th Infantry Regiment.

[1] In October 1898, he was promoted to temporary brigadier general of volunteers in the Spanish–American War.

[1][2] His daughter, Emma Baldwin, married Samuel Rockenbach, who also served in the 10th United States Cavalry.

[3] His son Theodore Anderson Baldwin Jr. (1878-1957) attained the rank of colonel as a career officer in the United States Army.