The 57th Foot. Their colonel (Inglis) in the battle of Albuera (1811), addressing his men, said, “Die hard, my lads; die hard!” And they did die hard, for their banner was pierced with thirty bullets. Only one officer out of twenty-four survived, and only 168 men out of 584. This fine regiment is now called the West Middlesex; the East Middlesex (the Duke of Cambridge's own) is the old 77th.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894