Born and raised in Luverne, Minnesota, to prepare for the ministry Johan Dahlen attended Augsburg University in Minneapolis, Minnesota. After graduating in 1930, he was ordained a Lutheran minister. He served as pastor of Palermo Lutheran Parish in Palermo, North Dakota, until entering military service early in World War II. He served with the 1st Infantry Division during the invasion of North Africa, serving in Oran, Kasserine, and Tunisia, and then landed with the Division during the invasion of Sicily. He returned with the Division to England and then participated in his third amphibious landing of the war at Normandy, France, on D-Day, earning a Silver Star on the first day of the invasion. After the war he pastored churches at Churches Ferry and Balfour, North Dakota, before retiring in 1970.