"under attack," by 1882; earlier and more etymologically it meant "prepared to fight" (late 15c.), and (of structures) "fitted with battlements" (late 14c.); past-participle adjective from embattle (v.).
Entries linking to embattled
embattle v.
late 14c., "prepare for a fight," from Old French embataillier "to prepare for battle," from assimilated form of en- (see en- (1)) + bataille (see battle (n.)). Related: Embattled; embattling. Originally of armies; of individuals as well since 1590s (first attested in Spenser).