Complex sentence: Even if it could, the German fleet would still be sufficiently powerful to inflict significant damage in any battle, sufficient damage that the enemy would be unable to maintain its other naval commitments and must suffer irreparable harm.
Split into simpler sentences: Even if it could, the German fleet would still be sufficiently powerful to inflict significant damage in any battle. Sufficient damage that the enemy would be unable to maintain its other naval commitments and must suffer irreparable harm.