With an authorised strength of around 900 personnel, like other Australian infantry battalions of the time, the battalion was formed around a nucleus of four rifle companies - designated 'A' through to 'D' - each consisting of three platoons. Basic training continued at Rutherford until early January 1940, when the battalion moved to Ingleburn, New South Wales. Apart from a brief period of embarkation leave, the battalion remained at Ingleburn until 5 May 1940 when the 2/12th embarked upon the Queen Mary, bound for the Middle East, along with the rest of the 18th Brigade, where they were to join the 6th Division; however, due to concerns about a possible invasion of the United Kingdom following the Fall of France, the 18th Brigade, including the 2/12th Battalion, was re-routed and subsequently arrived at Gourock, Scotland, on 17 June 1940. Later, they were moved to Salisbury Plain, being stationed around Lopcombe Corner, where they undertook defensive duties. In September the battalion was re-allocated to the 9th Division and the following month it was moved to Colchester, Essex.