The Japanese carried into the mountains thirteen artillery pieces and employed fifteen in the Battle of Oivi–Gorari at the end of the campaign. While Anderson reports that approximately 940 men were responsible for carrying the guns, ammunition and other paraphernalia across the Owen Stanleys, he concludes that, despite this burden: "Throughout the Kokoda campaign the Japanese held one distinct advantage over the Australians: artillery. The Japanese use of artillery pieces in each Kokoda battle was a force multiplier, and the Australians were never able to match the Japanese ranged weapons." He attributes around 35 per cent of the Australian casualties to the Japanese artillery but observes that the effect upon morale was perhaps of equal significance: "The helplessness felt by the men who were subjected to relentless bombardment without the means to retaliate sapped both their number and their spirit." Williams asserts that: "Japanese artillery provided an important, perhaps decisive, role on the battlefields of the Kokoda Track."