Bandoneón day is celebrated on 11 July each year in Argentina. This date was chosen to mark the birth of the man who is considered the “Supreme Bandoneón of Buenos Aires”, the musician Aníbal Troilo.
On 11 July 2005, the Congress of Argentina declared that date as National Bandoneón Day by law, and this was enacted on 18 May 2005. The proponents of this law were Francisco Torne, grandson of Zita Troilo, and the poet Horacio Ferrer, a friend of the musician and president and founder of the National Academy of Tango.
If you wants to read more about “Pichuco” here is a Biography by