Due to his holdings on the coast, Egawa Hidetatsu was involved in issues of coastal defences, critical to Japan at that time.

[3] Egawa Hidetatsu was put in charge of establishing the defense of Edo Bay against Western intrusions in 1839,[5] following the incident of the Morrison under Charles W. King in 1837.

[8] Egawa also designed and built the battery emplacements at the entrance of Edo harbour at Odaiba in 1853/54, following the 1853 visit of Commodore Perry and his promise to return the following year.

[10] Commodore Perry would effectively stop his fleet at Uraga, southward at the entrance of Edo Bay, fully prepared for hostilities if his negotiations with the Japanese failed.

[15] A theoretical synthesis of "Western knowledge" and "Eastern morality" would later be accomplished by Sakuma Shōzan and Yokoi Shōnan, in view of "controlling the barbarians with their own methods".