Despite the British victory, their position in Afghanistan was no longer tenable and the army began the difficult process of retreating back to Peshawar. Following the trail which was still littered with thousands of dead from the previous disastrous attempt of withdrawal by a British army in January, Nicholson's regiment was part of the final rear guard as the British force was harassed through the Khyber Pass. On 1 November 1842, Nicholson was briefly reunited with his younger brother Alexander, who had only arrived in India a few short months before and was now helping to escort the British force through the pass. Alexander's unit was ambushed and overwhelmed two days later and it was Nicholson who was the first to find the mutilated body of his younger brother. This disturbing experience, as well as his experience of the Afghan War as a whole, is said to have deeply affected Nicholson and left him with "an intense feeling of hatred" of Afghans and the entirety of India. Nicholson's first experience of war had also, however, instilled a "near-messianic sense of destiny" on him and he now believed it was his duty to spread Christian civilization onto what he considered a "heathen" land.