Erwin Louis Dann was born on 16 March 1896 in Burksville, Monroe County, Illinois. He was the son of Edward and Caroline (nee Kolter) Dann. After his father passed away in 1897, his mother married William Lohkamp in 1900. They all resided in Waterloo, Monroe County, Illinois with his older brother and younger sister.
Dann enlisted into Company F, 1st Missouri National Guard on 19 June 1916 in St. Louis, Missouri. He was 5’ 7”, had black hair, brown eyes, fair complexion, and weighed 148 pounds. With the National Defense Act of 1916 enacted on 03 June 1916, the 1st Missouri Infantry was inducted into Federal Service on 25 June 1916 and was the first regiment to Camp Clark, Nevada, Vernon County, Missouri. From there they departed to Laredo, Webb County, Texas on 01 July 1916 for the Mexican Punitive Expedition. Dann and his unit remained in Texas until 02 September 1916, returned to Camp Clark and mustered out of federal service on 25 September 1916.
On 26 March 1917, the 1st Missouri Infantry was mobilized in St. Louis and sent to Camp Clark. ; drafted into federal service 05 August 1917