"The fourth, or north-western division", at Ludhiana, was to operate in the hilly country lying near the Sutlej: it assembled under Brigadier-General Ochterlony, and was destined to advance against the strong and extensive cluster of posts held by Amar Singh and the troops under his immediate orders at and surrounding Irkee, a considerable town of Kahlur, and to cooperate with the forces under Major-General Gillespie, moving downwards among the hills, when these positions should be forced, surrounding Amar Singh, and driving him upon that army.