Leslie Jensen, a native of Hot Springs and the son of Black Hills pioneer Chris Jensen and Lillie May Haxby Jensen, was educated in Hot Springs, Culver Military Academy, and the University of South Dakota. He took an early interest in the military and served as a Lieutenant in the 4th South Dakota Infantry on the Mexican Border in 1916-17; when that organization became the 147th Field Artillery in World War I, he went to France with it as the Regimental Adjutant. Remaining with the 147th, he was its Lieutenant Colonel in 1937 when, as 15th Governor of South Dakota from 1937-1939, he became his own Commander-in-Chief. Promoted to Colonel in 1941, he took his regiment to the South Pacific in World War II, and when the regiment was battalionized in 1943, he served with distinction as a Base Commander on the staff of the Commanding General of the Sixth Army. In 1921 he was appointed Collector of Internal Revenue for the District of South Dakota, serving until 1934, when he returned to Hot Springs and to the telephone business his father had started in 1894. His administration in 1937 initiated a highway construction program of great economic and social benefit to South Dakota.