The 56th Battalion was originally formed on 14 February 1916 during the reorganisation and expansion of the First Australian Imperial Force (AIF) that took place in Egypt following the Gallipoli campaign.

Under the command of Lieutenant Colonel Allan Humphrey Scott, the battalion formed part of the 14th Brigade attached to the 5th Australian Division.

Arriving in Marseilles on 30 June 1916, the 56th Battalion was transported to northern France and within a fortnight was committed to the Battle of Fromelles, where the 5th Division undertook a disastrous attack that was later described as "the worst 24 hours in Australia's entire history".

After enduring the coldest winter in 40 years in the Somme, during early 1917 the battalion took part in the brief advance the Allies enjoyed as the Germans withdrew to the Hindenburg Line, before undertaking a defensive role during the Second Battle of Bullecourt, and then launching an attack at Polygon Wood in September.

[5] In early 1918, after wintering in Belgium, it was transferred south to France to assist in repulsing the major offensive the Germans launched on the Western Front following the capitulation of Tsarist Russia.

[8] During World War II, the 56th Battalion undertook garrison duties in New South Wales and Western Australia, as part of the 5th Brigade of the 2nd Division.

[11] Along with the 7th/21st Australian Horse it formed the basis of the reformed 4th Battalion, which was raised in 1958 and later became part of the Royal New South Wales Regiment.