Background
He was born in New Castle, Del. , in 1804, the son of Evan and Elizabeth (Sherer) Thomas.
He was born in New Castle, Del. , in 1804, the son of Evan and Elizabeth (Sherer) Thomas.
There was a military tradition in the Thomas family and in 1819 Lorenzo entered the United States Military Academy. At his graduation in 1823 he stood seventeenth in his class.
He was made a second lieutenant in the 4th Infantry. Subsequently he rose to the rank of major (1848) in this regiment. Except for service as quartermaster in the Seminole War (1836 - 37), his early duties were mostly of a routine nature. He was appointed assistant adjutant-general at Washington in 1838, with the rank of brevet major, and remained there almost continuously until 1846, when he joined the volunteer division of Maj. -Gen. William O. Butler as chief of staff during the Mexican War. "For gallant and meritorious conduct" at Monterey he was brevetted lieutenant-colonel, September 23, 1846. At the close of the war he returned to his duties as assistant adjutant-general at Washington and continued in that capacity until designated as chief of staff to Lieut. -Gen. Winfield Scott in 1853.
Upon the resignation of Col. Samuel Cooper, the adjutant-general of the army, Thomas was promoted to a colonelcy and put in charge of that office, March 7, 1861. Five months later he was made adjutant-general and given the rank of brigadier-general. Like other bureaus of the War Department, when the Civil War came, the office over which Thomas presided proved hopelessly inadequate in equipment and personnel and gradually had to be expanded. Meanwhile, he was subjected to sharp criticism from some of the zealous war governors because he seemed too slow in furnishing state quotas and other necessary information. There apparently was considerable laxity and inefficiency in his bureau and many persons surmised that he was "lukewarm" regarding the war, but there was no sound basis for this suspicion.
In what was probably an effort to be rid of him, Secretary Stanton ordered him to the Mississippi Valley in March 1863 to organize negro regiments. This work, together with arranging for the exchange of prisoners and the consolidation of depleted regiments, kept him occupied until the end of the war. He was brevetted major-general on March 13, 1865. The next year Stanton sent him on an inspection tour of the provost marshal general's office and in 1867 on an extended inspection tour of the national cemeteries. While he was engaged in the latter work the difficulties between President Johnson and Stanton came to a head, and the President, desiring to have a "rightminded" man in the adjutant general's office, directed Thomas on Febryary 13, 1868, to resume full charge of the bureau.
On February 21, Johnson dismissed Stanton, appointed Thomas secretary ad interim, and requested him to take possession of the department. The selection was unfortunate, for the Adjutant-General proved to be a vain and garrulous person. When he publicly boasted that he would oust the Secretary by force if necessary, Stanton ordered his arrest for violation of the Tenure of Office Act. Although immediately admitted to bail and discharged within a week, the General failed to displace the recalcitrant Secretary, the contest between them degenerating into opera bouffe. Thomas' testimony and his naïveté in the impeachment trial of the President effectively dispelled the charge that he and Johnson had conspired forcibly to eject Stanton and helped to win for the President an acquittal.
After the adjournment Thomas resumed his inspection duties, but was retired from active service on February 22, 1869. He died in Washington six years later.
He is remembered as a United States Army officer who was Adjutant General of the Army at the beginning of the American Civil War. After the war, he was appointed temporary Secretary of War by President Andrew Johnson, precipitating Johnson's impeachment. Fort Thomas, a military post established in Arizona Territory in 1876, was named for Thomas.
