Drummed out of the army
Dismissed from army service to the sound of a drum.
The phrase 'drummed out' is most often used in relation to the, now outmoded, military practice of dismissing disgraced soldiers to the sound of drums. This drew attention to their plight and acted as a warning to others. The earliest reference to 'drumming out' comes in a figurative use of the phrase, in Thomas Amory's The life of John Buncle, 1766:
"They ought to be drummed out of society."
Soon after that comes a piece from The Edinburgh Advertiser, (June 1776), which refers to a literal 'drumming out', that is, with drums:
"Included was a letter to me in very extraordinary language, and a summons to deliver up the town: the messenger was sent to prison for a few days, and drummed out."
The earliest specific reference to drumming out in a military scenario is Lord Thomas Macaulay's Critical and miscellaneous essays, 1829:
"Another is drummed out of a regiment."
These days we hear little of people being drummed out, apart from in the corny joke 'He was drummed out of the Mafia for cruelty'.