In 1754 Knox, still with the 43rd, purchased a lieutenancy and three years later left Ireland with his regiment for Halifax, Nova Scotia. The 43rd were initially intended to support the Earl of Loudon's operation against Louisbourg but this expedition never took place as a result of a combination of poor weather conditions and a strong French naval contingent. Nor did Knox's regiment take part in Amherst's successful campaign the following year. Instead, they spent those two years stationed at Fort Cumberland and around Annapolis.