Complex sentence: The day was misty and rainy, which grounded aircraft and led to the attack being postponed for a day and ground taken by an advance of two companies of the 55th Division was abandoned, after the French attack was repulsed.
Split into simpler sentences: The day was misty and rainy, which grounded aircraft and led to the attack being postponed for a day. Ground taken by an advance of two companies of the 55th Division was abandoned after the French attack was repulsed.