The Collaborative International Dictionary of English v.0.48:

Embattle \Em*bat"tle\, v. t. [imp. & p. p. Embattled; p. pr. &
   vb. n. Embattling.] [OF. embataillier; pref. em- (L. in) +
   F. bataille battle. See Battle, and cf. Battlement.]
   To arrange in order of battle; to array for battle; also, to
   prepare or arm for battle; to equip as for battle.
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         One in bright arms embattled full strong. --Spenser.
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         Here once the embattled farmers stood
         And fired the shot heard round the world. --Emerson.
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The Collaborative International Dictionary of English v.0.48:

Embattle \Em*bat"tle\, v. i.
   To be arrayed for battle. [Obs.]
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The Collaborative International Dictionary of English v.0.48:

Embattle \Em*bat"tle\, v. t. [See Battlement.]
   To furnish with battlements. "Embattled house." --Wordsworth.
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WordNet (r) 3.0 (2006):

embattle
    v 1: fortify by furnishing with battlements for defense; "an
         embattled castle"
    2: prepare for battle or conflict

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "embattle":
   arm, armor, armor-plate, bank, barricade, battle, blockade,
   bulwark, castellate, crenellate, dig in, entrench, fence, fortify,
   garrison, man, man the garrison, mine, palisade, wall