Iwaz was the first to realise the importance of a navy for a riverine country like Bengal and built a flotilla of war-boats to face any aggression. For defence as well as for administrative purposes, he connected the capital city with the outlying towns of Devkot and Lakhnur by an embankment with ferries on the Ganges and other rivers. In order to protect his kingdom from the annual floods he constructed a series of dykes with arched bridges.