The Southern Front, also called the Malayan Front, is generally described as being the theater of the Pacific War contested by the Japanese and Oceanians throughout the Malayan archipelago and in northern Australia. This front tends to blend with campaigns in the eastern Oceanic Front. Fighting in the Malayas began in October of 1924 with the Japanese surprise attack against the Oceanian First Fleet in the Malayas during the Hallowe'en Raids and continued with the all-out invasion of Sumatra and Java from Japanese bases in Borneo and Sarawak. The Oceanians were forced to abandon Batavia on Christmas Day after the Oceanian general Lord David Hall reached an agreement with the Japanese 3rd Imperial Army to allow his men to retreat peacefully back to Australia, ceding the strategic city.
Oceanian skirmishes continued throughout early 1925 as the Japanese began preparations for their invasion of the United States, which they correctly viewed as the greater threat. Chinese and Korean soldiers were sent to the Malayas and to New Guinea to help subjugate the island, but Port Moresby held out surprisingly long, depleting Japanese supplies and attention that could have been paid to the United States. The fall of Port Moresby was viewed as a symbolic victory for the Oceanians, who with the protection of the Malayan people there began to earn the trust of the greater Malayan culture.
The attempted Japanese invasion of Australia following aerial and sea bombardments of coastal settlements was a strategic failure, typified in the Battle of Darwin where they failed to hold onto three beachheads with astronomical loss of life. The failure of the Japanese to hold Darwin, as well as the attention paid by the Japanese to the Americas, allowed the Oceanians time to recuperate and retake Port Moresby in early 1926, a major strategic and moral victory. In late 1926 and early 1927, in the Second Battle of Java, the Oceanians drove the Japanese out of Batavia (now Jayakarta) and back into Sumatra, where the Japanese had a much less firm presence. Coupled with various other tactical errors on the parts of the Asians as well as American victories in Hawai'i and in Midway, the Japanese fell into retreat from the Malayas (save northern Sumatra) and the Battle of Sumatra, which would last until 1929, became the final focii of the front, with the Allies electing not to launch an offensive against Borneo, which was sparsely populated and whose military bases were abandoned by the Japanese in late 1927 and early 1928 for fear of being cut off after initial Allied successes in the south Philippines, in particular naval success. Borneo and Celebes were never attacked by Allied soldiers and their inclusion in the Japanese Empire was (oddly, according to some historians) never disputed by Allied negotiators, even Oceanian ones.