While William Jefferson Gatewood is known more prominently as the first publisher of the San Diego Union, his earlier history involved serving with the Illinois Mounted Volunteers during the Mexican-American War in 1847-1848. Once mustered out he headed to California for the Gold Rush ending up in San Andreas, where he started his law practice. He had a famous duel in 1859 with Dr. Peterson Goodwyn who was a Southern sympathizer and had called Greenwood "a damned abolitionist". Hubert Howe Bancroft writes that as Goodwyn lay dying, he replied to Greenwood "I am glad to know that you acted like a gentleman." He was also the publisher of The San Andreas Register from 1861 to 1868 when he left for San Diego and started the San Diego Union. In this letter, to Congressman Denver (whose name graced the city in Colorado), he is asking as a lawyer for information on behalf of Michael B. Cunningham who had served in Company C of the Massachusetts 4th, Heavy Artillery Regiment. His request is for a copy of the discharge or a certified copy. He ads: "the soldiers here have confidence in you and are proud that your name has taken an upward political boom." Creasing from folds.