linguistic:translation
19th century

At the time of independence, Uruguay had an estimated population of just under 75,000. The political scene in Uruguay became split between two parties: the conservative Blancos (Whites), headed by the second President Manuel Oribe, representing the agricultural interests of the countryside, and the liberal Colorados (Reds), led by the first President Fructuoso Rivera, representing the business interests of Montevideo. The Uruguayan parties received support from warring political factions in neighboring Argentina, which became involved in Uruguayan affairs.

The Colorados favored the exiled Argentine liberal Unitarios, many of whom had taken refuge in Montevideo, while the Blanco president Manuel Oribe was a close friend of the Argentine ruler Manuel de Rosas. On 15 June 1838, an army led by the Colorado leader Rivera overthrew President Oribe, who fled to Argentina. Rivera declared war on Rosas in 1839. The conflict would last 13 years and become known as the Guerra Grande (the Great War).

In 1843, an Argentine army overran Uruguay on Oribe's behalf but failed to take the capital. The siege of Montevideo, began in February 1843 and lasted nine years. The besieged Uruguayans called on resident foreigners for help, which led to a French and an Italian legion being formed, the latter led by the exiled Giuseppe Garibaldi.

In 1845, Britain and France intervened against Rosas to restore commerce to normal levels in the region. Their efforts proved ineffective, and by 1849, tired of the war, both withdrew after signing a treaty favorable to Rosas. It appeared that Montevideo would finally fall when an uprising against Rosas, led by Justo José de Urquiza, governor of Argentina's Entre Ríos Province, began. The Brazilian intervention in May 1851 on behalf of the Colorados, combined with the uprising, changed the situation, and Oribe was defeated. The siege of Montevideo was lifted, and the Guerra Grande finally came to an end. Montevideo rewarded Brazil's support by signing treaties that confirmed Brazil's right to intervene in Uruguay's internal affairs.

In accordance with the 1851 treaties, Brazil intervened militarily in Uruguay as often as it deemed necessary. In 1865, the Triple Alliance was formed by the emperor of Brazil, the president of Argentina, and the Colorado general Venancio Flores, the Uruguayan head of government whom they both had helped to gain power. The Triple Alliance declared war on the Paraguayan leader Francisco Solano López. The resulting Paraguayan War ended with the invasion of Paraguay and its defeat by the armies of the three countries. Montevideo was used as a supply station by the Brazilian navy, and it experienced a period of prosperity and relative calm during the war.

The first railway line was assembled in Uruguay in 1867, and a branch consisting of a horse-drawn train was opened. The present-day State Railways Administration of Uruguay maintains 2,900 km of extendable railway network.

The constitutional government of General Lorenzo Batlle y Grau (1868–72) suppressed the Revolution of the Lances by the Blancos. After two years of struggle, a peace agreement was signed in 1872 that gave the Blancos a share in the emoluments and functions of government through control of four of the departments of Uruguay.

This establishment of the policy of co-participation represented the search for a new formula of compromise based on the coexistence of the party in power and the opposition party.

Despite this agreement, the Colorado rule was threatened by the failed Tricolor Revolution in 1875 and the Revolution of the Quebracho in 1886.

The Colorado effort to reduce Blancos to only three departments caused a Blanco uprising of 1897, which ended with creating 16 departments, of which the Blancos now had control over six. Blancos were given ⅓ seats in Congress. This division of power lasted until President Jose Batlle y Ordonez instituted his political reforms, which caused the last uprising by Blancos in 1904 that ended with the Battle of Masoller and the death of Blanco leader Aparicio Saravia.

Between 1875 and 1890, the military became the center of power. During this authoritarian period, the government took steps toward the organization of the country as a modern state, encouraging its economic and social transformation. Pressure groups (consisting mainly of businessmen, hacendados, and industrialists) were organized and had a strong influence on the government. A transition period (1886–90) followed, during which politicians began recovering lost ground, and some civilian participation in government occurred.

After the Guerra Grande, there was a sharp rise in the number of immigrants, primarily from Italy and Spain. By 1879, the total population of the country was over 438,500. The economy reflected a steep upswing (if demonstrated graphically, above all other related economic determinants) in livestock raising and exports. Montevideo became a major financial center of the region and an entrepôt for goods from Argentina, Brazil, and Paraguay.