The resulting power vacuums in the weeks following the Japanese surrender, created an atmosphere of uncertainty, but also one of opportunity for the Republicans. Many "pemuda" joined pro-Republic struggle groups ("badan perjuangan"). The most disciplined were soldiers from the Japanese-formed but disbanded "Giyugun" (PETA, volunteer army) and "Heiho" (local soldiers employed by Japanese armed forces) groups. Many groups were undisciplined, due to both the circumstances of their formation and what they perceived as revolutionary spirit. In the first weeks, Japanese troops often withdrew from urban areas to avoid confrontations.