The holiday commemorates the Battle of Vuelta de Obligado which took place on November 20th 1845 when the Argentine Confederation fought against an Anglo-French navy in the Battle of Vuelta de Obligado, during the Anglo-French blockade of the Río de la Plata. 

The Argentine Confederation lost the battle, but there is a saying ‘lose the battle but win the war’ and this was true in this case. Despite the victory, the British and French suffered such heavy losses that the battle brought them to negotiate a treaty with Juan Manuel de Rosas, the Governor of Buenos Aires. 

The battle was seen as a key event as it had been triggered by Argentine efforts to protect regional industries from colonial powers in the region by raising trading tariffs and efforts by de Rosas to get Uruguay and Paraguay to join the confederation antagonised the French and British and led to the battle. 

November 20th has been nationally observed as the Day of National Sovereignty since 1974, but the fourth Monday only became a national holiday in 2010.