ROSAS, Juan Manuel de (ro'-sas). Argentine dictator, born in Buenos Ayres, 30 March, 1793; died in Swathling, Southampton, England, 14 March, 1877. He belonged to a noble family that owned large cattle farms, but he received only a limited education, and from his youth took part in the work of his father's farm. During the English invasion he served until the evacuation of Buenos Ayres and Montevideo, when he returned to the country to take charge of his father's property. When Governor Rodriguez, of Buenos Ayres, was threatened with invasion in 1820 by the governors of Santa Fe and Entre Rios, he appointed Rosas captain of militia, and the latter, with a force of 600 gauchos, assisted in the battles of San Nicolas and Pavon. Afterward he was appointed commander-in-chief of the southern frontier against the Pampas Indians. Under President Rivadavia he was appointed commander-in-chief of all the forces of the province of Buenos Ayres, but later he joined the insurrectionary forces against the government, and Rivadavia resigned in consequence. He was a sustainer of the Federal administration of Dorrego, and when the government of the latter was overthrown by Lavalle, Rosas joined the forces of Governor Lopez against Lavalle. The legislature of Buenos Ayres appointed Rosas governor on 6 December, 1829. Although nominally he sustained the Federal principle, his government soon became arbitrary, and numerous executions of his political enemies took place by his orders. At the expiration of his term in December, 1832, he resigned in the expectation of being re-elected, but the legislature took him at his word and chose General Balcarec. Rosas immediately began an active opposition, and, tired of continual strife, Balcarec resigned in 1833, as also did his successor, Colonel Viamonte, soon afterward. Several other governors were elected by the legislature, but, fearing the vengeance of Rosas. were afraid to accept, so that the president of the legislature, Manuel Vicente Maza, took charge provisionally of the executive. The representatives of the province elected Rosas governor in 1835 with extraordinary powers, and on 13 April he began a tyrannical dictatorship, which ended only with his flight in 1852. Soon he formed alliances with some of the governors of the interior, and those that resisted his authority he vanquished, so that he became arbiter of the destiny of all the Argentine Republic. Two of the principal Federal chiefs, Quiroga and Lopez, died suddenly, and it was suspected that Rosas caused their death. He now remained undisputed chief of his party, and turned his attention against the Centralization party, or Unitarians, whom he persecuted cruelly. When Oribe's government fell there, in October, 1838, and President Rivera favored the Argentine refugees, Rosas declared war against him, and in July, 1839, invaded the territory of that republic with 7.000 men. Although his army was at first defeated, and Gem Lavalle invaded the Argentine at the head of an army, Rosas organized a force the command of which he gave to General Oribe, and began a war against the Unitarian chiefs of the interior, and a price was set on their heads. A law was promulgated that every one, male and female, should use a red ribbon as the badge of the Federal party, and all political documents were headed with the words " Long live the holy federation : death to the savage Unitarians." In January, 1843, General Oribe, at the head of an Argentine army of 14,000 men, invaded the republic of Uruguay again, and the siege of Montevideo, which lasted for nearly nine years, began. France and England interfered, and the blockade of Buenos Ayres began on 18 September, 1845, but Rosas resisted the demands of the allies until, in November, 1849, a treaty favorable to the dictator was signed. This treaty left the navigation of La Plata, Uruguay, and upper Parana rivers entirely in the hands of the province of Buenos Ayres, excluding even the interior provinces, and this caused general dissatisfaction, especially in the river provinces of Entre Rios and Corrientes. The governor of the former, General Urquiza, published a manifesto on 1 May, 1851, inviting all the provinces to throw off the yoke of the dictator, and on 29 May he concluded an offensive and defensive alliance with Brazil and Uruguay. Assisted by the money and army of Brazil, he marched against Rosas's army in Uruguay, and after he had defeated Oribe the troops of the latter joined him. Re-enforced in this manner, and assisted by the Brazilian fleet, he marched with 30,000 men against Buenos Ayres. Rosas, with an army of about equal force, was intrenched at Palermo and Santos Lugares, but at the first attack of Urquiza his troops wavered. They were defeated, 3 February, 1852, at Monte Caseros, and Rosas escaped on board a foreign vessel to England, where he afterward lived in retirement. In 1859 the Argentine congress ordered proceedings to be instituted against him, and on 17 April, 1861, sentence was pronounced, condemning him to death as a " professional murderer and famous robber." In this trial 2,034 assassinations, by his personal orders, were proved against him, while the historian, Jose Rivera Indarte (q. v.), gives a detailed account of 22,405 victims of Rosas's policy.