Complex sentence: After the artillery firing ceased, no one knew if the bombardment was to continue so the attack was launched at the scheduled time, giving the Turkish defenders ample time to return to their trenches and prepare for the assault that they now knew was coming.
Split into simpler sentences: After the artillery firing ceased, no one knew if the bombardment was to continue. As a result, the attack was launched at the scheduled time, giving the Turkish defenders ample time to return to their trenches and prepare for the assault that they now knew was coming.