They fought against the enemy.
Karera wa teki to tatakatta.
they (usually male); them
topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis
opponent; rival; adversary; menace; danger; threat; enemy
if; when; and; with; particle used for quoting (with speech, thoughts, etc.); quoting particle; promoted pawn; indicates question (sentence end)
to make war (on); to wage war (against); to go to war (with); to fight (with); to do battle (against); to compete (against); to struggle (against adversities, etc.); to fight; to contend; to resist