The pictures are prison cells, how the prisoners were kept and the place were many head went off. Sender's note - "for our people in Manipur so that they have an idea what real patriotism is like".
The Hoa Lo Prison, later sarcastically known to American prisoners of war as the "Hanoi Hilton", was a prison used by the French colonists in Vietnam for political prisoners and later by North Vietnam for prisoners of war during the Vietnam War.
Picture Credit :: Shanta Nahakpam - shantaanta12(at)gmail(dot)com