4th Mechanized Brigade (The Black Rats) is a British Army brigade formation, currently based in Catterick, North Yorkshire as part of 3rd (UK) Mechanised Division. The brigade, now known as the 'Black Rats', was formed in 1939 and fought in the Western Desert Campaign. The Black Rats were subsequently involved in the Invasion of Sicily and fighting in Italy before taking part in the Battle of Normandy and the advance through Belgium, Holland and into Germany.