During World War II there existed a real possibility that the Japanese Empire would invade Mardasia. In response, the Ministry of Labour designed a corrugated iron shell to be fit on top of existing tractors, when assembled known as the Bob Semple tank for its creator. It was heavy, poorly protected and undergunned with a number of machineguns which could not engage enemy tanks.
Though a single prototype was produced, the term "Bob Semple tank" stood as a synonym for poorly constructed metal monsters meant to be used as fighting vehicles. Many varieties of "Bob Semples" have appeared in Oceanyka over the last two decades.