The 46th Battalion was originally formed on 24 February 1916,[3] during the First World War, as part of the expansion of the Australian Imperial Force (AIF) which occurred in Egypt at the conclusion of the Gallipoli Campaign.

[5] The battalion's first major battle came at Pozières in August, initially carrying ammunition for the troops of the 2nd Division when they attacked, before later undertaking defensive duties to hold the gains that were made.

[7] As part of the pursuit of the Germans once they had withdrawn to the Hindenburg Line, the attack was initially successful as the 46th managed to break through to its objective, but it was eventually pushed back as a result of its heavy casualties.

[5] In early 1918, it was transferred south to France where it played a defensive role during the German spring offensive, seeing action around Dernancourt in April.

[5] Its final attack of the war was made in mid-September 1918 against the outposts of the Hindenburg Line, after which the battalion was withdrawn from the front for reorganisation and training; it was joined by the rest of the Australian Corps in early October.

[13] These changes, along with the economic downturn of the Great Depression which limited training opportunities, greatly affected the availability of manpower at the time and as a result a number of units were amalgamated at this time,[14] although the 46th Battalion was not one of those selected for this fate and it remained on the order of battle, albeit with limited personnel, until the outbreak of the Second World War.

Following Japan's entry into the war in December 1941, however, the tempo was increased and in March 1942 the battalion was moved to Queensland along with the rest of the 4th Brigade to conduct garrison duties.