These two units had previously existed as separate entities with their own lineages that can be traced back to the earliest infantry units raised in New South Wales prior to Federation, which participated in a number of conflicts including the Mahdist War, the Boer War, and the First World War. By virtue of these predecessor units, the 1st/19th Battalion is the custodian of a number of battle honours from these conflicts. The battalion also maintains the battle honours of a number of units from the Second World War. Even though during the conflict the 1st Battalion was not deployed overseas on active service, the 19th Battalion was, being sent to New Guinea in 1944 and then later taking part in the New Britain campaign. The 1st/19th Battalion also maintains the battle honours of two Second Australian Imperial Force units, the &lt;a href="2/1st%20Battalion%20%28Australia%29"&gt;2/1st&lt;/a&gt; and &lt;a href="2/19th%20Battalion%20%28Australia%29"&gt;2/19th Battalions&lt;/a&gt;, which served in North Africa, Greece, New Guinea, Malaya and Borneo.