to shake (from fear, cold, excitement, etc.); to shudder; to tremble
「戦く」 has another reading with different meanings.
敵の足音に村人は戦いた。
The villagers trembled at the sound of the enemy's footsteps.
寒さに戦いて、彼女は毛布を引き寄せた。
Shuddering from the cold, she pulled the blanket tighter.
この規模の戦いを前に、歴戦の兵士でさえ戦く。
Even seasoned soldiers tremble before a battle of this scale.