Myrmidons of the Law
Bailiffs, sheriffs' officers, and other law menials. Any rough fellow employed to annoy another is the employer's myrmidon.
The Myrmidons were a people of Thessaly who followed Achilles to the siege of Troy, and were distinguished for their savage brutality, rude behaviour, and thirst for rapine.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894