What motivates soldiers in war field? To fight valiantly! With enormous vigor! Leaving behind their family and wealth at home! Being ready to sacrifice their precious lives!
Is it patriotism? Is it money? Is it fame? Is it ego? Is it satisfaction? Is it a sense of purpose?
Hmmm.. apparently, the most powerful force behind the soldiers' motivation is friendship. They see their friends, with whom they have spent their life 24x7, lying next to them, lifeless with eternal silence or screaming with acute pain for life. The adrenalin rush the soldier experiences can make him do the impossible! This is also well portrayed in the recent movie -
Oh, yeah! The director of the Ranjni film also used this logic to magically transform Manikkam into Baadsha.