Complex sentence: This battle prevented the Japanese Navy from resupplying their troops in the Marianas leaving a brutal war of attrition for the Japanese until the commanding general Saito committed suicide and the island was declared liberated on 9 July 1944.
Split into simpler sentences: This battle prevented the Japanese Navy from resupplying their troops in the Marianas. What was left was a brutal war of attrition for the Japanese until the commanding general Saito committed suicide and the island was declared liberated on 9 July 1944.