The 'pom pom' was a 37mm (1.45in.) autocannon that fell somewhere between quick-firing artillery and an infantry support weapon. It saw action in the Boer war and was deployed as an anti-aircraft weapon in WWII. The gun itself weighed 410 pounds and it was used on a carriage. It is essentially an enlarged version of the Maxim machine gun. It is known as the pom pom due to the distinct noise it made when fired.