The unit was created on November 26, 1936, at the Madrid front, from the "Ferrer", "Toledo", "Sigüenza", "7th Confederate Militias", "Orobón Fernández" and "Juvenil Libertario" battalions of the Palacios Column.[n.

1] Miguel Palacios Martínez was appointed as commander of the 39th Mixed Brigade, with the anarcho-syndicalist Julián Adrados Almazán as political commissar.

[5] The 39th MB received reinforcements from the Durruti Column, the brigade being yielded by the "Juvenil Libertario" and "Orobón Femández" battalions.

During the rest of 1937, Mariano Román Urquiri and Álvaro Gil del Moral passed through command of the brigade.

[5] On April 24, the 39th MB was sent as reinforcements to the Segorbe sector, then marching to the front line in the vicinity of Allepuz, where it joined the 14th Division of the 21st Army Corps.