Complex sentence: Night attacks were less hazardous and there were times when air attack was able to delay and even suspend traffic across the straits but when daylight returned, the Axis were able to clear the backlog from the previous night.
Split into simpler sentences: Night attacks were less hazardous, and there were times when air attack was able to delay and even suspend traffic across the straits. However, when daylight returned, the Axis were able to clear the backlog from the previous night.