"Brander's telegram setting out his plans reached Macdonald at New Chumbi on 3 May and he sought to reverse the action, but it was too late.The battle at Karo La on 5–6 May is possibly the highest altitude action in history, won by Gurkha riflemen of the 8th Gurkhas and sepoys of the 32nd Sikh Pioneers who had climbed and then fought at an altitude in excess of 5,700 m.

Meanwhile, an estimated 800 Tibetans attacked the Chang Lo garrison.