Ajax originally played in an all-black uniform with a red sash tied around the players' waists, but that uniform was soon replaced by a red/white striped shirt and black shorts. Red, black and white are the three colours of the flag of Amsterdam.
When under manager Jack Kirwan, however, the club earned promotion to the top flight of Dutch football for the first time in 1911 (then the Eerste Klasse or 'First Class', later named the Eredivisie), Ajax were forced to change their colours because Sparta Rotterdam already had exactly the same outfit. Special kits for away fixtures did not exist at the time and according to football association regulations the newcomers had to change their colours if two teams in the same league had identical uniforms. Ajax opted for white shorts and white shirt with a broad, vertical red stripe over chest and back, which still is Ajax's outfit.
