There are many short incidents about Hari Singh Nalwa, donno if true.
One is about him in peshawar, he along with some 20-30 singhs were attacked by around 200 pathans. Being short in number, the Sikhs took shelter in a nearby haveli. They asked for the peace terms but the Pathans were for Nalwa.
At night it rained a lot. In the early morning, the singhs saw local people hammering their mud roofs. When he asked, someone told that the local mitti was called "kuttan mitti" bcoz whenever it rained, they had to do this exercise otherwise it leaked.
So Hari Singh Nalwa said that those pathans were made of the same Mitti.... so the only way to keep them under control is to hammer them regularly. So all of Sikhs attacked the pathans with full vigour and after some time all of them were asking peace from the Sikhs.
jis no saajan raakhasee dhusaman kavan bichaar ||
What harm can a helpless enemy do one whom the Lord protects?
shhaioo n sakai thih shhaahi ka nihafal jaae gavaar || 24||
(The enemy) cannot strike even his shadow. (Such an action) by the fool proves futile.(24)
- Guru Gobind Singh Ji
PS: There was a mistake in Sakhi 108 ( Guru Angad and King Humayun) . It is beleived that Guru ji was busy teaching the students and not in prayers (as was mentioned in the sakhi series version ). Apologies for the mistake.