Analysis of information sources in references of the Wikipedia article "Second siege of Anandpur" in English language version.
Before any fight took place Guru Gobind Singh had about 10,000 men. However, they were not well equipped. On the other hand, the Mughal army was consisted of over a hundred thousand well-equipped men. Moreover, they were accustomed to fighting and could face the troubles and hardships of war.
It appears highly likely, moreover, that dharam occasionally lost out to the more brute contingencies of the day that raj demanded, as we note in the multiple raids led by Sikhs in the closing years of the seventeenth century and the opening years of the eighteenth against villages such as, for example, Alsun (which was ransacked after the Battle of Nadaun) in the Pahari kingdoms adjoining Anandpur, something about which Sri Gur- Sobha also speaks, though in a highly sanitized manner.