Originally, Chillán Viejo was the location of a Spanish fort with the name of San Ildefonso, which was established in 1565, during the campaign of Pedro de Villagra against Loble and the Mapuche north of the Biobío River. Ordered in 1579 to establish a city at the site by GovernorRodrigo de Quiroga, Martin Ruiz de Gamboa founded the city on June 25, 1580 after replacing Quiroga as governor following his death. He gave it the name San Bartolomé de Chillán y Gamboa and populated it with 50 Spaniards and 60 more in the fort. It suffered a number of attacks before it was destroyed by the Mapuche in 1599 after the Disaster of Curalaba. Governor Francisco de Quiñónez immediately repaired it in April 1599. Later, in 1655, the same Mapuche and the neighboring Pehuenches forced the citizens to abandon it again. When it was again reoccupied, it was demolished by an earthquake on March 15, 1657. It was repopulated again in 1663, under Ángel de Saldia. The earthquake of May 25, 1751, that ruined old Concepcion, also damaged the city, aggravated considerably by a simultaneous extraordinary flooding of the Chillán River. This forced its transfer two years later to the site that it occupies today. It acquired some fame during the Chilean War of Independence, especially in the Siege of Chillan from July 15 to August 12, 1813, after the death in her of the Spanish leader, Antonio Pareja, and it was sacked by the royalist montoneras of Pincheira on September 18, 1819. It became the capital of the Chillán Department and after it was ruined in the earthquake of February 20, 1835, most of its population was moved to the northeast to form the present city of Chillán.
Demographics
According to the 2002 census of the National Statistics Institute, Chillán Viejo spans an area of and has 22,084 inhabitants. Of these, 18,827 lived in urban areas and 3,257 in rural areas. Between the 1992 and 2002 censuses, the population grew by 32.1%. The 2017 census showed that the total population for the commune was 30,907. The demonym for a person from Chillán Viejo is Chillanvejano or Chillanvejana for a woman. ; Notable Chillanvejanos Chillán Viejo was the birthplace of Francisco Núñez de Pineda y Bascuñán in 1607 and Bernardo O'Higgins in 1778.
Within the electoral divisions of Chile, Chillán Viejo is represented in the Chamber of Deputies by Carlos Abel Jarpa and Rosauro Martínez as part of the 41st electoral district,. The commune is represented in the Senate by Victor Pérez Varela and Mariano Ruiz-Esquide Jara as part of the 13th senatorial constituency.
