The Gunners
In 1886 a group of workers at the Royal Arsenal armaments factory in Woolwich, south-east London, started a football team and called it Dial Square. The club soon became Royal Arsenal, later Woolwich Arsenal, and dropped the Woolwich in 1913.
The factory made weapons, and the nickname stuck: Arsenal are the Gunners, and the cannon on the club crest is a nod to the same story.