In 1913 Frederick Bailey, an intelligence officer with the Indian Army, invited Morshead to be the surveyor in an expedition to explore the Yarlung Tsangpo Grand Canyon (Tsangpo Gorge), now known to be the world's deepest gorge.
In doing this they proved that the Dibang tributary of the Brahmaputra flows around rather than through the Himalayan mountains and does not connect with the Tsangpo.