In 1837 he happened to be in Herat in Afghanistan to gather intelligence on the area when the Persian army, supported by Russians, laid siege to the city.

After some years of regimental duty he was appointed to the political department under his uncle, Colonel (afterwards knighted and promoted to Lieutenant General) Henry Pottinger.

Arriving at Herat, he found it threatened by a Persian army (with whom were some Russian officers) and immediately made himself known to the Afghan commander, offering his services.

Taking refuge with the Gurkha garrison of Charikar, Major Pottinger withstood a siege of fourteen days, and then made an adventurous retreat to Kabul.

Pottinger himself was one of the hostages handed over to Akbar Khan, and thus escaped the near-total massacre of the retreating British and Sepoy troops in the evacuation from Kabul to Jelalabad in January 1842.