On 23 June, an initial order was given for a company of the 39th Battalion to deploy to Kokoda with the possibility of it being joined by the rest of the battalion. This was amended on 24 June for deployment of the battalion (less one company). The instrument for this was NGF Operational Instruction 18. It placed the PIB under command of the 39th Battalion. It also assigned detachments of service units in support. Attachments were placed under command of Lieutenant Colonel William Owen, commanding officer of the 39th Battalion. "Maroubra" was assigned as the code word. An advance party, the battalion's B Company, assembled at Illolo. Departing on 8 July, it arrived at Kokoda on 15 July.