allow his forces to recuperate and resupply before restarting the drive on Buin. After repelling more futile Japanese attacks in the 17 April – 22 May Battle of the Hongorai River, his men crossed the Hari and Mobai Rivers. However, shortly after reaching the Mivo River their advance came to a halt as torrential rain and flooding washed away many of the bridges and roads upon which the Australian line of communications depended. This rendered large scale infantry operations impossible for almost a month and it was not until late July and into early August that the Australians were able to resume patrolling across the Mivo River. Before Savige could mount a substantial assault, news arrived of the dropping of the atomic bombs, after which the Australian forces mainly only conducted limited patrolling actions. Conclusion Combat operations on Bougainville ended with the surrender of Japanese forces on Bougainville on 21 August 1945. The Empire surrendered in Tokyo Bay on 2 September 1945. The last phase of the campaign saw 516 Australians killed and another 1,572 wounded. 8,500 Japanese were killed at the same time, while disease and malnutrition killed another 9,800 and some 23,500 troops and labourers surrendered at the end of the war. Of the casualties suffered during the second phase of the campaign, historian Harry Gailey wrote: "it was a terrible toll for an island whose possession after March 1944 was of no consequence in bringing the war to a close ... That the Australian soldiers performed so well when they had to know that what they were doing was in the larger sphere unnecessary and unappreciated at home says much for the courage and the discipline of the ordinary Australian infantryman". In contrast, Australian historian Karl James has argued that the 1944–45 Bougainville campaign was justifiable given that it could not be known at the time that Japan would surrender in August 1945, and there was a need to both free up Australian forces for operations elsewhere and liberate the island's civilian population. Of the civilian population, according to James it is estimated that potentially up to 13,000 of the pre-war population of 52,000 died during the war. Hank Nelson estimated that 25 percent of the civilian population died during the war, with most deaths occurring after 1943. Three Victoria Crosses were awarded during the campaign, one to a Fijian and two to Australians. Corporal Sefanaia Sukanaivalu