Herbert Eggleston received a battle field commission in World War II, and earned a Silver Star as an Infantry officer with the 24th Infantry Division. Following his war service he was discharged and served in the U.S. Army Reserve. A long time lay worker at the First Presbyterian Church in Pomona, California, before the war, after his war service he spent a year at the San Francisco Theological Seminary in San Anselmo, California, and then attended Andover Newton Theological Seminary in Massachusetts, and was ordained a Presbyterian minister in 1948. He and his wife began missionary work in Hawaii, and in October 1947 he became pastor of the historic Kalihi Union Church in Honolulu, where he ministered for several years. He was director of Christian Education at Hickam (Hawaii) Air Force Base Chapel, and worked with the 10th Aeromedical Evacuation Squadron there. He also initiated and carried out a volunteer counseling service at Hawaii State Prison.