William Joseph Leonard Nicodemus was born August 1st, 1834, in Clear Spring Dist., near Hagerstown, Maryland. His father Frederick Nicodemus (March 20, 1806 to April 20, 1858) and mother Mary Ann Kessler (Feb 4, 1805 to Aug 17, 1849) were married April 18, 1833 in Martinsburg, Berkeley Co, Virginia. William was the eldist of two children, his sister Anne was born in 1840. On February 21, 1850 William's father Frederick, was re-married to Mary Ann Medcalf in Washington County, Maryland. From this marriage, two half brothers Alfred M. born September 1854 and Edward M. born August 1858, and a half sister Laura born in 1851 were brought into the family.
William first applied to West Point in January of 1852 at seventeen years of age. His actual appointment, two years later was made as a result of a letter from Maryland Representative William Hamilton in April 1854. Representative Hamilton’s letter to then U.S. Secretary of War, Jefferson Davis, (who later became President of the Confederate States of America) recommended appointing William “in place of” another applicant. He entered West Point July 1, 1854, just one month shy of his 20th birthday.
On July 1, 1858, William J. L. Nicodemus graduated from the United States Military Academy at West Point, 23rd out of 27 in his senior class, just three months after his fathers death and was promoted in the Army to brevet Second Lieutenant of Infantry. His first assignment was with the 5th Infantry at the garrison at Newport Barracks, Kentucky. On January 19, 1859 he was promoted to Second Lieutenant. During 1859 and into 1860, he participated in the Utah Expedition.
In 1860, William and his unit found themselves in New Mexico where he served at various posts. Fort Fauntleroy, New Mexico, Fort Defiance, New Mexico, and Fort Union, New Mexico, in 1861.
During this time William first served with Albert J. Myer, a "civilian in uniform" and Army Surgeon, developing aerial telegraphy communications, and was instructed in his signal methods. On February 7th, 1861, while on duty at Fort Fauntleroy, New Mexico, Lieut. Nicodemus was stationed upon a prominent point on the lookout for a wagon train, at this time a feat was performed which deserves mention. An order was given by signal for the detachment to "fall in," and then they were practised in the manual of arms, each movement being called by the flag. The succeeding day they were employed in observation of the Albuquerque road, orders having been issued to look for the appearance of any parties in that direction. Communications were then established over a line thirty miles in extent. This duty occupied the command until Feb. 10th, when the party was recalled by signal headquarters.
As hostilities broke out in 1861, William was promoted to First Lieutenant, 11th Infantry and later, Captain, 12th Infantry, acting also as Assistant Adjutant General of the Department of New Mexico from October 1861 to June 1862. For gallant and meritorious services at the Battle of Valverde, New Mexico in February 1862, he was given a brevet promotion to Major. The Battle of Valverde was fought on February 21, 1862 and was the first major conflict in the Intermountain West. The battle was filled with intensive combat and full of valiant individual acts and tragedies. The South claimed it as a victory, but the losses were high on both sides. Each army spent the next two days under flags of truce to “care for their wounded and burying their dead on the battlefield near the Rio Grande”.
In September 1862, William was ordered transferred to Cincinnati because word of an impending attack upon the city. Shortly thereafter, he was made Regimental Commander of the 4th Maryland Volunteers. With that position came the rank of full Colonel. This was certainly a big step, but it was not at all unknown during the Civil War, especially for a graduate of West Point.
William was a regimental commander for only six weeks when he wrote a letter in his own hand to the Commanding General of the 8th Army Corps resigning his command. The letter states:
It is unsure what the reason for this resignation was, but is spectulated to be related to the removal of McClellan as commander after the tragedy at Antietam. A roster of the 4th Maryland Volunteer Regiment shows that other officers in the regiment also resigned shortly after McClellan’s removal. First Lieutenant John A. Thompson, Jr. resigned on November 12th and Major Henry P. Brooks, resigned in early December. Whether or not McClellan’s removal was the reason for any of these resignations, after resigning his command, William reverted to his permanent rank of Captain.
Albert J. Myer, the Signal Officer to which William had been detailed in New Mexico, continued with his signal duties. It appeared that the 37th Congress would soon pass a bill, officially establishing the Signal Corps as its own branch of the Army. On January 15, 1863 Major Myer wrote to Captain Nicodemus who was then on recruiting duty in Philadelphia, Pennsylvania informing him that a Signal Corps “Camp of Instruction” was to be established near Georgetown. Myer wrote:
William could not at once accede to the request, but on January 27th an application for the detail of Capt. Nicodemus was forwarded to the Secretary of War. One month later, February 27th, 1863, Captain William J. L. Nicodemus assumed command of the Signal Corps Camp of Instruction on Red Hill, Georgetown, D.C. This camp was the forerunner of the U.S. Army Signal School established at Fort Monmouth, New Jersey and later moved to its present location, Fort Gordon, Georgia.
In summer of 1863, with the Southern forces making ever-bolder encroachments into the North, William was given command of a Signal detachment that operated in West Virginia and Maryland in support of the Army of the Potomac. Later, he supported General Meade whose victory at Gettysburg was less than a month old. During this period, he was in charge of communications between Harper’s Ferry, Virginia and Washington, D.C., participating in several skirmishes while pursuing the enemy through Maryland.
On July 6th, 1863, under the command of Capt. W. J. L. Nicodemus, a signal detachment, consisting of twelve officers and twenty-seven enlisted men, arriving from Washington, and was immediately united with a signal party then in service of reconnoissance of the southern retreat from Gettysburg. Gen. Meade ordered Capt. Nicodemus to the front, which was then the South Mountian Pass, to the field, with the following instructions: "You will open communications between Frederick City and South Mountian Pass, and establish observation stations to command the Boonsboro Valley." The next day, July 8th, 1863, Capt. Nicodemus broke up the stations along the route as fast as the telegraphic communication was established. On September 18, 1863 William was promoted to Major, Signal Corps.
On November 10, 1863 Albert Myer was relieved of the command of the Signal Corps by the Secretary of War, Edwin Stanton. Brigadier General Edward Canby was directed by Stanton to audit the accounts of the Signal Corps. General Canby three years earlier in the campaign against the Navajo had been the first commander in the U.S. Army to witness the use of “signals” in combat. His audit results showed that the receipts and expenditures of the Signal Corps balanced perfectly.
On November 15, 1863, Major Nicodemus was appointed in Myer’s place and assumed command of the Corps. For the first and only time during the war, the US had a West Point graduate at the helm, whereas, the CSA started with a West Pointer. In May, he moved his office to a larger building and installed the Signal Corps’ first printing press. The next summer, on August 10, 1864, William was promoted to Lieutenant Colonel, Signal Corps. (some sources put his date of promotion as June 30  and July 3, 1864). Lieutenant Colonel Myer was also reappointed as Colonel, Signal Corps at this time, and continued to serve as “Signal Officer of the Army”.
William kept very busy in his new job. He was active in recruiting and staffing the Signal Corps. He was continuously fighting for recognition for the Corps’ capabilities. He fought a constant battle with the Secretary of War to get his troops properly promoted and otherwise rewarded for their service. On more than one occasion he wrote Secretary Stanton about the “great injustice” done by promotion boards.
The Signal Corps’ new printing press was used to publish the required hundreds of copies of orders, circulars, and letters addressed to signal officers in the field. In December 1864, William, in his annual report, criticized the West Point authorities for their attitude toward military signaling and “boldly” recommended that the field telegraph trains be returned to the Signal Corps. He had the report printed and then distributed copies throughout the Signal Corps without the prior approval of the Secretary of War. “This, though innocently done brought the thunder and lightning down upon his head”.
Secretary Stanton was well known for his powerful temper. When he learned of the distribution of a report which he had not yet seen, his reaction was instant and typical. Stanton sent a detachment of troops to take over the Signal Office, seize the printing press, the original manuscript, and all printed copies. By order of the Secretary of War, General Order 304 dismissed Lieutenant Colonel William J. L. Nicodemus from the service on December 26, 1864. Another key aspect, which very well may have led to his dismissal, was the fact that William had referred, in a half dozen places, the fact that the US was reading CSA signal messages. William published this sensitive information in "unclassified" documents. He probably knew, or at least assumed, that the CSA already knew the fact, but this gave Stanton grounds for "aid and confort to the enemy" in an area in which the Chief of the Signal Corps should have been hypersensitive to.
On December 27, 1864, just one day after his dismissal from the Army, at the Trinity Church in Georgetown, D.C., William took Frances “Fannie” E. Pettit as his wife.
On March 31, 1865, William J. L. Nicodemus was reappointed as Lieutenant Colonel, Signal Corps by order of the President of the United States in General Order No. 53, War Department Adjutant General’s Office, and was honorably mustered out of the service Aug. 23rd 1865. He was then restored to his regiment, the 12th Infantry, as Captain, the rank he had last held with his regiment before being detailed to signal duties in February, 1863.
After the War, William J. L. served at Fort Hamilton, New York harbor, Richmond, Petersburg, and Fredricksburg, Virginia, and again in Washington, D.C. In 1869, he was detailed from the Regular Army as military instructor at Western University in Pittsburgh, Pennsylvania. On December 29, 1870, he was honorably discharged from the United States Army at his own request.
Directly upon his discharge, William worked as a professor of civil and mechanical engineering at the University of Wisconsin. C.W. Butterfield, in his History of the University of Wisconsin, writes of William Nicodemus:
Reportedly, William had more than one offer to leave his professorship at the university. One offer he received was from General William Tecumseh Sherman, with whom he was well acquainted. General Sherman asked William to accept a position as professor at a college just being started by the “Khedive of Egypt”. The pay was reportedly twenty-five hundred dollars per annum, in gold.
Post war, Professor Nicodemus rarely spoke of himself or of his many experiences. Possessed of a large store of nervous force, he rapidly and efficiently accomplished whatever he took in hand. Ambitious to provide for the wants of his family, should they ever be left without his care, he felt pressed to engage in business enterprises outside the duties of his professorship. As he was never slack in his duty to the University, he must have drawn very largely on his vitality, to accomplish the work he undertook. This is more especially true of the past university year, when burdened more than usually with the needs for instruction in his growing department, and with his work for geological survey, he shared largely in the risks, and anxieties consequent on publishing, along with A. D. Conover, a large and very accurate map of Wisconsin. The draft on his nervous system proved great, and brought on insomnia, which finally developed alarmingly.
William Joseph Leonard Nicodemus died January 6, 1879 near Madison, Wisconsin, at just 45 years old. He was buried near Madison in the Catholic cemetery of Forrest Hill. He left his wife of 15 years and four children, R. Canby (perhaps named after General E. R. S. Canby with whom William had served out west and in Washington) born 1866, Lillian M. born 1871, Grace A. born 1874, and Bertha J. born 1875.