By the time the Indian battalion reached the Thag La Ridge area in the Chedong region on 16 September, north of the McMahon Line, Chinese units controlled both banks of the Namkha Chu valley. The day after, India's Chief of the Army Staff Gen P N Thapar ordered his men to re-take the Thag La Ridge. According to the official Indian history, on 20 September, Indian eastern command ordered all Indian posts and patrols to engage any Chinese patrols within range of their weapons. On 20 September, at one of the bridges on the river a firefight developed, killing nine Chinese and Indian soldiers. Skirmishes continued throughout September.