The man on the envelope, Daniel Christiansen, was born in 1904 and died in 1994, putting him in his 60s or 70s when some of this was made. He was a native of Skodsborg, Denmark, arrived in the US aboard the ship Olympic in 1927. Enlisted in the US Army in 1942 at Fort Dix. Got out in 1945. His occupation at the time was carpenter. I haven't been able to learn much about his later life, but it looks like he didn't have any family and lived in a pretty crappy neighborhood.