There were three different pants wore by the British army during the War of 1812. First you have the white breeches with black gaiters, for parade use only. Then you have white trousers, which could be used with grey half gaiters, or black knee gaiters, either underneath or on top of the pants' sleeves. Finally, you had the grey trousers, which also could only be worn with grey half gaiters, either on top or underneath.