The entire campaign hung on a transmitter. Count Maximilian von Spee's East Asia Squadron was loose somewhere in the Pacific, and as long as German wireless stations at Rabaul and the Caroline Islands could feed it information, the squadron could threaten Allied merchant shipping across half the world. Britain asked Australia to silence those stations. The Australian Naval and Military Expeditionary Force, hastily raised in Sydney in August 1914, was the answer. Most of its infantrymen had enlisted only weeks earlier. Many had never fired a rifle in anger. On 11 September they came ashore at Kabakaul and the old German gubernatorial capital of Herbertshöhe, the place we now call Kokopo, and began pushing inland toward a rumoured radio station at Bita Paka. They did not find it easily. A mixed force of German reservists and Melanesian police contested every hundred yards of jungle track.

By the time the Australians reached the wireless station that evening, seven of them were dead. The defenders had left the transmitter largely intact but taken down the mast. Australia's first major military engagement of the war had been won, at a cost that looked small beside what was coming on the Western Front but was disproportionate to what had been gained. About thirty Melanesian policemen had also been killed fighting for a colonial power not their own, a detail that would haunt later accounts. Years afterward, allegations would surface that Australians had bayoneted captured Melanesian prisoners at Bita Paka. Two days after the fighting, on 14 September, the submarine HMAS AE1 vanished off Rabaul with all thirty-five men aboard. The war in the Pacific had begun, and already its ledger was uneven.

The surviving German defenders pulled back nineteen miles through dense bush to Toma, a small hill settlement where Governor Haber set up what remained of the colonial administration. He was waiting for von Spee. If the East Asia Squadron could reach Rabaul, it might yet relieve the garrison, turn the campaign around, and hold German New Guinea for the Kaiser. What Haber did not know was that a detachment of 200 Australians under Major Edward Fowell Martin had followed him up the Toma road, dragging a single 12-pounder naval gun. They spread themselves in the bush and moved into positions around the town. The protected cruiser moved into supporting range offshore. Then the field gun opened fire on Toma, and the cruiser added its shells to the nearby ridges, and the Australian show began.

The shelling was, more than anything, theatre. The 12-pounder was one gun. Two hundred men scattered through jungle could not have held off a determined counter-attack. But the noise was enough. Haber, looking out from Toma at what sounded like a substantial attacking force, understood that he was alone. Von Spee was not coming. The East Asia Squadron was in fact already in retreat across the Pacific, bound eventually for destruction off the Falkland Islands in December. Negotiations opened almost immediately. On 15 September Haber rode down to Herbertshohe to meet Colonel William Holmes, the Australian commander. Terms were signed on 17 September. The last forty German soldiers and 110 Melanesian police laid down their arms on 21 September. A New York Times piece later described the whole affair as the German governors being saved by an Australian bluff.

Most of the Germans in the colony were interned and deported. A single stubborn holdout, Leutnant Hermann Detzner, took twenty Melanesian police into the interior of mainland New Guinea and evaded capture for the entire war, emerging in 1919 to an already-changed world. German New Guinea passed to Australian military administration, then to a League of Nations mandate in 1921, and eventually became part of modern Papua New Guinea at independence in 1975. The siege of Toma is often called bloodless, and the action itself was. The campaign that led to it was not. Seven Australian families received telegrams in September 1914. Around thirty Melanesian families never received anything at all. The hill station where Governor Haber surrendered sits today in quiet tropical country, a small highland village beneath the volcanic cone of the Baining ranges, four days of its history long folded into deeper ones.