This is about the Sino-Sikh War The Wikipedia article says
He had extended his communication and supply line over 450 miles of inhospitable terrain by building small forts and pickets along the way. The fort Chi-T’ang was built near Taklakot, where Mehta Basti Ram was put in command of 500 men, with 8 or 9 cannon. With the onset of winter all the passes were blocked and roads snowed in. The supplies for the Dogra army over such a long distance failed despite Zorawar’s meticulous preparations.
As the intense cold, coupled with the rain, snow and lightning continued for weeks upon weeks, many of the soldiers lost their fingers and toes to frostbite. Others starved to death, while some burnt the wooden stock of their muskets to warm themselves. The Tibetans and their Chinese allies regrouped and advanced to give battle, bypassing the Dogra fort of Chi-T’ang.
Is there more knowledge, on how their supplies failed, even after preparing? Besides, Nepal was only 15 miles from Taklakot, and they had had friendly relations with Sikh Empire, then why were they not helped?