page_title: Revolution of 11 September 1852
section_title: Counterrevolution and siege of Buenos Aires
hierarchical_section_title: Revolution of 11 September 1852 / Counterrevolution and siege of Buenos Aires
caption_attribution_description: Español: Hilario Lagos
context_page_description: The Revolution of 11 September 1852 was a conflict between the Province of Buenos Aires and the government of Justo José de Urquiza, after the latter triumphed over Juan Manuel de Rosas at the Battle of Caseros.
  A period known as "National Organization" was initiated after the Battle of Caseros. Every political faction agreed on authorizing a national Constitution. However, in opposition to the rest of the country, the ruling upper class in Buenos Aires aspired to impose political requirements on the Argentine provinces, so as to maintain the traditional political and economic preeminence of the capital city.
  The result was a ten-year separation between the Argentine Confederation and the State of Buenos Aires. Both states claimed to be part of a single nation, but in reality they behaved like separate states.
context_section_description: On December 1st, standing in front of the campaign troops, Colonel Hilario Lagos spoke against Alsina's government in Guardia de Luján, today Mercedes. The major part of the rest of the campaign commanders, like Costa, Bustos or Flores, spoke in favor of Lagos. Basically, they demanded the reincorporation of the province to the Confederation, and Alsina's resignation and replacement by General Flores.
  On December 6, Alsina presented his resignation and was replaced by general Pinto. The same day, Lagos' troops attacked the city, but the quick reaction of many determined leaders, specially Mitre, stopped them from seizing the Capital. Two days later, Lagos laid officially the siege to Buenos Aires city.
  Many leaders who had collaborated with Alsina's downfall, like Lorenzo Torres, refused to accept Flores' or Lagos' authority, and least of all and agreement with Urquiza. In such way that, leaving behind their internal conflicts, they collaborated on defending the city. Torres himself took over the Government Ministry at the end of December.
  Three weeks later, Urquiza sent support troops to Lagos, so he reinforced the siege but couldn't breach the resistance of the Porteña infantry with his almost exclusively cavalry troops. Moreover, the Government of the city sent a prestigious campaign chief, Pedro Rosas y Belgrano, to gather the troops that remained loyal in the interior of the province. These were totally defeated in the Battle of San Gregorio, on January 22, in part because Urquiza's squad had also blocked Buenos Aires city by the side of the River Plate, a few days before the battle.
  During some months, the city of Buenos Aires remained besieged and isolated, but its financial superiority kept if safe from the sieger's attacks. A treaty signed on March 9th between Buenos Aires government and the Constituent Congress set the peace conditions between the State of Buenos Aires and the Confederation, but did so in conditions that both Urquiza and Lagos considered negative for the Confederation: it left the income from customs in the hands of Buenos Aires and allowed this province to elect up to 10 Representatives. Which is to say, it favored Buenos Aires precisely in the two matters that were more disputed between this and the rest of the provinces. The treaty was ultimately rejected, and Urquiza reinforced his military support to the siege, incorporating himself into it.
  On May 1st, the Congress sanctioned at last, the National Constitution. In the following months it would be sworn on by every Argentine province, Buenos Aires included: the official news was never sent to the city of Buenos Aires, but to the military and political commander of the interior, General Lagos. He hastily assembled a legislature, which officially sanctioned the National Constitution. The government of the city completely rejected the Constitution.
  In the end of April, General Urquiza had taken advantage of the venality of Porteños naval commanders to buy their defection to the Buenos Aires cause, and completely block the port of Buenos Aires. But Urquiza's strategy backfired on June 20th: the commander of the fleet John Halstead Coe, sold himself for a huge amount of money to the porteños, and handed them almost all the fleet.
  The failure of the blockage had an enormous demoralizing effect on sieging troops. A few days later, general Flores, who had abandoned the siege, returned to the north of the province with a huge sum of money, with which he bought a large part of Lagos' troops. On July 12th, Urquiza abandoned the siege of Buenos Aires, followed by General Lagos himself and part of his troops.
  The siege had failed.
caption: Federales Col. Hilario Lagos fought with the Confederation against the new State.
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