In August 1947 at the time of invasion of J & K by Pak raiders, the entire northern frontier of Jammu and Kashmir State from Bunji to Leh, approximately 200 miles (excluding Gilgit Agency) was manned by the 6th Battalion. After the fall of Bunji in early November 1947, the 6th Battalion was ordered to move to Skardu with as many troops as possible.

On 11 February 1948, Skardu was attacked and surrounded by the enemy of approximately 600 strong strength. The encmy was routed under the determined leadership of Lieutenant Colonel Sher Jung Thapa. Unable to capture the fort, the enemy laid to seige to the fort, which continued for six months. Despite dwindling rations, ammunition, shortage of water, lack of medicines, heavy casualties and other overwhelming odds, the enemy attempts to capture the fort were thwarted every time under the dynamic and inspiring leadership of Lieutenant Colonel Sher Jung Thapa. After going through the seige for long and when not help of any kind could be given from outside, Lieutenant Colonel Sher Jung Thapa was asked by Maj Gen K S Thimayya, DSO, GOC 19 Infantry Division to surrender which he stoutly opposed and continued to hold on the fort steadfastly without any regard to his personal safety.

On the fateful day of 14 Aug 1948, the gallant survivors of the 6th, utterly exhausted and on the verge of starvation, out-numbered to 5 to 1, without ammunition, rations and any hope of succour from outside, had no alternative but to capitulate. Thus ended the heroic seige of Skardu which had kept a superior enemy at bay for six months and three days. For this gallant action, Lieutenant Colonel later Brigadier Sher Jung Thapa was awarded MVC.