The "Trieste" brigade's history began in August 1862 when the Infantry Brigade "Valtellina" was raised. The brigade consisted of the 65th Infantry Regiment "Valtellina" and the 66th Infantry Regiment "Valtellina". The brigade along with the Infantry Brigade "Brescia" formed the 5th Division of the Line in the Third Italian War of Independence, where it fought in the Battle of Custoza. Personnel from the brigade was dispatched to fight in the Italian colonial wars in Eritrea in 1887, Abyssinia in 1895 and Libya in 1911.