After the May Thirtieth Movement riots, which resulted in a police massacre, Fairbairn was charged with developing an auxiliary squad for riot control and aggressive policing. After absorbing the most appropriate elements from a variety of martial-arts experts, from China, Japan and elsewhere, he condensed these arts into a practical combat system he called Defendu. He and his police team went on to field-test these skills on the streets of Shanghai; Fairbairn himself used his combat system effectively in over 2000 documented encounters, including over 600 lethal-force engagements.[2] The aim of his combat system was simply to be as brutally effective as possible.