Explanation:

 The easy success of Mir Jumla was due to dissatisfaction in the Assam camp. The leading commanders and the officers were the exclusive monopolies of the Tai-Ahom. But. King Jayadhwaj Singha had appointed a Kayastha as viceroy of Western Assam and commander-in-chief of the Ahom army despatch against Mir Jumla leading to resentment among the ranks. This officer was Manthir Bharali Barua of Bejdoloi family. He was also appointed Parbatia Phukan. This appointment caused bitter resentment among the hereditary Ahom nobles and commanders and the resistance which they offered to the invaders was neither worthy of the efficient military organisation of the Ahoms nor of the reputation which they acquired by repeated success in their enterprises against foreigners, and Mir Jumla’s march into Assam was an uninterrupted series of triumph and victories though the real secret of his success, namely, defection in Ahom camp, which has not been touched upon by any historian of the expedition.