In 1932, which animal 'beat' the Australian military in the so-called Great War?

Answer

Soldiers with machine guns failed to cull large numbers of emus and withdrew in what became known as the Emu War.

Context

The Emu War was a 1932 military operation in Western Australia. After World War I, the government settled thousands of veterans on marginal farmland, and a drought and falling wheat prices followed. Roughly 20,000 emus, according to National Geographic, moved into farmland in search of water and damaged crops and fences, and farmers appealed for help.

The government sent soldiers from the Royal Australian Artillery with two Lewis light machine guns under Major G. P. W. Meredith. The campaign began in early November 1932 and was called off after roughly six weeks. The emus split into small groups and ran fast over open ground, which made them hard to target, and the guns were inefficient against moving flocks. National Geographic reports about 30 emus killed in the first three days and roughly 2,500 by the end, though the reported kill numbers vary between sources.

The label 'war' was applied by journalists and has stuck, but the military did not formally lose a conflict. The operation attracted criticism, including from people concerned about the animals' welfare. Farmers' complaints continued afterward, and the state later turned to bounties and fencing rather than machine guns. The episode is better described as a failed pest-control operation than a defeat by an enemy.