Since the beginning of the War, the Fire Nation had searched for a way to conquer the capital of the Earth Kingdom, Ba Sing Se; however, all previous attempts had failed. The country hoped that, by conquering the city, the Earth Kingdom would be severely crippled once the Council of Five and the Earth King were taken out of power. A successful subjugation also meant conquering the last safe place for refugees displaced by the War. Late in the War, the Fire Nation forced a refugee and Earth Kingdom mechanist to make weapons, including the drill, to aid them in battles by threatening to burn his home if he refused.