Mid 19th century; earliest use found in The Glasgow Herald. From the name of the Crimea + shirt, probably so called on account of its warmth (and occasioned by the topicality of the Crimean War).
Definition of Crimea shirt in US English:
Crimea shirt
nounkrʌɪˌmɪə ˈʃəːt
Crimean shirt.
Origin
Mid 19th century; earliest use found in The Glasgow Herald. From the name of the Crimea + shirt, probably so called on account of its warmth (and occasioned by the topicality of the Crimean War).