The Imperial Japanese Army started developing small gunboats for close support of amphibious landings in 1924 and by 1927 had the AB-Tei gunboat. By WWII these would be diesel-powered. They would be transported to the landing zones on merchant ships. They were also used as patrol boats in rivers, harbors and coastal zones and to escort supply barges. In this role they encountered PT boats. The ‘57 mm’ guns were actually the Japanese Type 97 47 mm anti-tank gun or a British 6 pdr. Contains 4 gunboats and state cards. —description from the publisher