Complex sentence: The number of prisoners necessitated this selective policy which envisaged trials of those with the strongest commitment to Bose' ideologies, while those with less strong views and other extenuating circumstances would be dealt with more leniently, with the punishment proportional to their commitment or war crimes.
Split into simpler sentences: The number of prisoners necessitated this selective policy which anticipated trials of those with the strongest commitment to Bose's ideologies. Those with lesser commitment or other extenuating circumstances would be dealt with more leniently, with the punishment proportional to their commitment or war crimes.