After Sirik Matak had sacked Keo An , a dissident academic , Lon Non organised a series of vocal student demonstrations against him calling for his removal .
By March 1972 , Lon Nol and his brother had managed to drive Sirik Matak from power .
After Sirik Matak had sacked Keo An , a dissident academic , Lon Non organised a series of vocal student demonstrations against Lon Nol calling for Lon Nol 's removal .
By March 1972 , Lon Nol and his brother had managed to drive Sirik Matak from power .