These days, most mustering is about courage or passing: ‘I mustered the courage to speak up’ or ‘that comment doesn’t pass muster.’ But originally it referred to a formal gathering of troops for inspection. Medieval armies would call all their soldiers together to check no one was AWOL, and that they were all properly armed and fit for duty – and that was called ‘a muster’.
14th-century ‘muster rolls’ show sheriffs and commanders doing just that: assembling the county’s able-bodied men, checking weapons and recording who turned up (muster rolls are not to be confused with roll calls, which are when someone reads aloud the names of the people on the muster roll to check who’s there).
‘Muster’ has other military uses too – when a military unit is created, it’s ‘mustered in’, and when it’s disbanded, it’s ‘mustered out’.
This is of course where we get the phrase ‘passing muster’ from, which has been around since the late 16th century, although then it was ‘pass the muster’. It wasn’t long until we dropped the ‘the’, and started using ‘muster’ in a more figurative, non-military way to mean ‘to gain acceptance or approval’.
‘Muster’ comes from a Latin word, ‘monstrare’, which means ‘to show’. This passed into Old French as ‘mostrer’ and then into Middle English as ‘muster’.
During Jubilee years, British armed forces perform a muster for the king or queen. This tradition dates back to Tudor times, and gives the military a chance to show the monarch what they do and what they look like. The 2012 Diamond Jubilee Armed Forces Parade and Muster was the first time all three service branches were present at the same time to celebrate Elizabeth II’s years on the throne. 2,500 servicemen and women took part in it, and it was the first major event of the Diamond Jubilee.