The Harriers Column of the FAI, or Los Aguiluchos, was the last of the great Catalan anarcho-syndicalist columns. Later, more militias left Catalonia for the front, but they would no longer do so in the form of a column but rather as reinforcement units of the existing columns. This column was supposed to form a large unit - of around 10,000 combatants - but it ended up reinforcing the Ascaso Column as an autonomous column - with about 1,500 militiamen with 200 militiawomen. Organized in the Bakunin barracks in Barcelona, it was sent to the Huesca front on 28 August, with Juan García Oliver and Miguel García Vivancos leading the column.