Mark Brooks Calnon, Sr. was born in Meridian, Idaho on August 21, 1918 to Clarence and Jessie Calnon. After graduating from Meridian High School he moved to Moscow to study agriculture at the University of Idaho. Calnon lived on campus at Willis Sweet Hall.

Calnon graduated from the university in 1940. Instead of waiting to be drafted into World War II, he volunteer for the Army Air Corps. After serving as a weather observer, Calnon found himself training to become a B-17 pilot. When he was sent overseas to England, he flew in the Eight Air Force.

On October 9, 1943, Calnon's B-17 was shot down. From his crew, three were killed and four were found wounded. Calnon himself survived the bailout, only to be taken prisoner by the Germans. Interned at Stalag Luft III, Calnon was witness to “The Great Escape” of 1944. This mass escape was led by Royal Air Force Squadron Leader Roger Bushell. Of the 76 escapees, 73 were captured and half were killed. As the war progressed, the airmen officers held in Stalag Luft III were transferred to Stalag VII-A in Moosburg, Germany. Here conditions worsened. American forces finally liberated Stalag VII-A on April 29, 1945.

After his military service, Calnon married Helen Ann Sutton. They had two children, Kathleen and Mark, Jr. Calnon worked as an agriculture extension agent for U of I in Ada county, managing 4-H programs until his retirement in 1973. He resided at the family farm in Meridian, Idaho until his death on May 11, 2015.