Actually they weren't even demonstrating. It was a gathering of people from inside and outside Amritsar, who came there for a festival. The order against gather

Actually they weren't even demonstrating. It was a gathering of people from inside and outside Amritsar, who came there for a festival. The order against gatherings of more than 4 people weren't distributed well, and so most of those people weren't aware of the order. Dyer then went and ordered the massacre.