After completing their service, they were mustered out of the military.
muster out
Frequency:
70
%
He mustered out from the army last year.
muster out
Frequency:
60
%
They mustered out the remaining soldiers after the war ended.
Idiomatic Expressions for muster out
Phrase: muster out of
Meaning: to leave or retire from a particular organization or group
Usage: After many years of service, he decided to muster out of the company and pursue other opportunities.