SWEENY, Thomas William, soldier, born in Cork, Ireland, 25 December, 1820. He came to the United States in 1832, and at an early age was apprenticed to the printing business. When a young man he joined the Baxter blues, a military organization in New York city, and in 1846, at the beginning of the war with Mexico, he became 2d lieutenant in Ward B. Burnett's 1st New York volunteers. He participated in the campaign under G en. Winfield Scott from the siege of Vera Cruz to the storming of Churubusco, where he received wounds that necessitated the amputation of his right arm. On his return to New York city he was given a reception ball at Castle Garden by the printers of the city, and he received the brevet of captain from the governor of the state and a silver medal from the city of New York. He was given the commission of 2d lieutenant in the 2d United States infantry, and served in California, in charge of Fort Yuma, and elsewhere in the west, being engaged in frequent actions with hostile Indians. While stationed at Fort Yuma, the command under Major Samuel P. Heintzelman was compelled to fall back on San Diego for want of supplies, and Sweeny was ordered to remain with ten men. The Indians besieged his camp from 5 June until 6 December, 1851, but he was finally extricated by a government exploring expedition under Captain Lorenzo Sitgreaves. After other duties at various posts he was promoted captain, 19 January, 1861. Soon after the beginning of the civil war he was ordered to St. Louis and given command of the arsenal, which contained immense quantities of munitions of war of all kinds, sufficient fully to arm and equip 60,000 men, together with over forty tons of powder. Captain Sweeny had but forty unassigned recruits under him, while in St. Louis there were nearly 3,000 hostile minute-men, fully equipped. Advances were made to induce him to surrender the arsenal ; but the reply, that if a serious attempt should be made to capture the arsenal he would blow it to atoms, prevented any action on the part of the Confederate sympathizers. He was second in command of the Union troops at the surrender of the state forces at Camp Jackson, and conducted the final negotiations, in consequence of General Nathaniel Lyon's having been disabled. Subsequently he was instrumental in the organization of the Missouri three-months' volunteers, and he was up-pointed brigadier-general on 20 May, 1861. In the campaign that followed he took an active part with General Lyon, and was severely wounded at the battle of Wilson's Creek, and later he was acting assistant adjutant-general under General John C. Fremont. He then accepted the command of the 52d Illinois volunteers, and was attached to the army under General Grant, participating in the capture of Fort Donelson, after which he took 6,000 prisoners to Alton, Ilk At a critical moment toward the close of the first day of the battle of Shiloh a gap existed between the right flank of Sweeny's brigade and General William T. Sherman's left. The defence of this position, which was the key of the situation, was intrusted to him by Sherman, who has since said : "I attach more importance to that event than to any of the hundred achievements which I have since heard saved the day." His commission of brigadier-general of volunteers dates from 29 November, 1862, and thereafter he commanded a division of the 16th army corps and was engaged in protecting the Memphis and Charleston railroad. He was promoted major of the 16th infantry, 20 October, 1863, and in the Atlanta campaign had the 2d division of the 16th corps in the Army of the Tennessee. At Snake Creek gap his command took possession of the gap twenty-four hours in advance of the cavalry, and held it in spite of every effort of the enemy. He took part in the battle of Resaca and forced a passage across Oostenaula river at Lay's Ferry, where he fought a successful battle, which action resulted in General Joseph E. Johnston's retreat southward. He also participated in the battles of Dallas and Kenesaw Mountain, and at the battle before Atlanta on 22 July, 1864, his division drove the enemy back with great slaughter, capturing four battle-flags and 900 prisoners. Subsequently he had command of the post of Nashville until July, 1865, and he was mustered out of volunteer service on 24 August of that year. He participated in the Fenian invasion of Canada in 1866, and was present at the battle of Limestone Ridge. During this period he was out of the National service, but was reinstated by the president soon afterward and given posts in the southern states. General Sweeny was presented with a sword by the city of Brooklyn for services rendered in the civil war. He was retired on 11 May, 1870, with the rank of brigadier-general.