Could not find a WW1 draft record for either son. I have some more info I recieved from someone about where the sons were born.
Abraham Valdemar Jensen was born June 17 in Vor Frue Sogn in Aalborg, Denmark. I think the year was 1860. Carl August Jensen born July 23 1861 in Vor Frue Sogn. Also, says that Sophie gave birth to two more sons.. in Vor Frue sogn in Aalborg. 29 nov 1863 Johannes Georg Jensen was born and 8 august 1865 Johannes Hulgaard Jensen was born. Johannes died at 6 weeks old.
This information was sent to me from someone. I can send you the document if you would like. It is mainly on Sophias family. They could not find info on Christian. I do not have the death record for Christian yet. I have found him in the South Dakota death index on Ancestry. So will hopefully be able to get it soon. Hope this helps. If you need anything else just let me know