"Idiots" would be the label Sui Xiong gave to the aristocrats who ridiculously decided to start a war in the evening.
Normally, the fact that it was dark was an equal disadvantage to both parties in war.
However, since the new merchant troops were well trained, they would be more familiar with collaborations with each other in war. Even if it were dark, the diminishing of the abilities would only be slight and rather negligible.
On the other hand, it was different for the aristocrats. Their elite troops were all from different parts of their land, and even though they had a few exercises together, they were not as familiar with each other as the merchant troops, who had had long term intensive trainings together. Even if they fought in the morning, they would still be at a disadvantage, much less at night!
Why did the aristocrats go crazy and decide to wage war in the night, then!?