Drummond very quickly demonstrated great promise and talent as an officer. In 1794, having been in the Army for only five years, Drummond served as a junior lieutenant-colonel in the Netherlands, commanded by the Duke of York himself. Drummond also saw service in the Mediterranean and the West Indies 1805, a mere 33 years old, Drummond had attained the senior rank of major-general and was well on his way to an extremely promising military career.
Before the Anglo-American War (also known as the War of 1812) that would seal Drummond's modest fame, Drummond spent three years serving in Canada just before the conflict, as a colonel's chief of staff. However, before the first shots were fired in the 1812 campaign, Drummond was reassigned, to Northern Ireland. The obvious benefits to the morale and pride of local militias by having a senior Canadian-born officer in Canada in the event of war seems to have eluded the British commanders, or else have been considered a low priority compared to having Drummond on hand in Northern Ireland. Drummond spent the entire first year of the war as an interested observer in Ireland, unable to take action on the battle waging in his homeland. While Drummond was in Ireland, one Lieutenant-Governor of Upper Canada (Isaac Brock) was killed at the Battle of Queenston Heights, and two more (Roger Hale Sheaffe and Francis de Rottenburg) circled through the post in less than two years.
Late in 1813, Drummond was reassigned to Upper Canada to replace Swiss-born de Rottenburg, an unpopular officer who was considered over-cautious, nervous about any sort of engagement, and reluctant to send reinforcements to vital areas (ironically, criticisms that would be levelled after the war at Rottenburg's superior, Sir George Prevost). Rottenburg would remain in Canada as part of the war effort (later to serve under Prevost as second-in-command during the 1814 campaigns), but Drummond would become Lieutenant-Governor of Upper Canada. Drummond immediately proved himself to be a general more in the mould of Isaac Brock than George Prevost. Aggressive and willing to take chances, December saw Drummond launch a surprise attack on Fort Niagara, surprising the American garrison and taking the fort easily.
Drummond also took after Brock as a civil leader, but there were some cardinal differences. While Brock was capable of using several means to convince the population to follow and (eventually) idolize him, Drummond ruled to a large extent by intimidation. Traitors or those suspected of aiding the Americans in any way could expect no mercy from the Lieutenant-Governor. Executions were relatively commonplace, and preformed publically. While Brock is once reported to have shed tears while watching a traitor executed by firing squad, Drummond displayed no such feelings. Despite these occaisonal displays of brutal and sudden punishment, Drummond was typically respectful of the citizenry as a whole, recognizing that their help would be essential in driving the Americans out of Canada.
Drummond, like fellow British commanders Brock and Henry Procter, was continually hungry for reinforcements from Prevost, who held relatively large numbers of troops in reserve at of Quebec, despite the fact that no troops had even come close to endangering the capital. Despite a constant lack of manpower and war material, Drummond had all but driven the American forces off of the Niagara by the close of the 1813-14 winter campaign. In July 1814, responding to a request from the beleaguered Major-General Phineas Riall, Drummond went with his troops from York to Fort George to take command from Riall and drive back Winfield Scott's invading soldiers. He ordered an immediate attack on the American forces, which were already engaging Riall's troops near Chippawa. In this way, a small skirmish exploded into the bloody and inconclusive Battle of Lundy's Lane, which cost each side over 850 casualties and left the British in possession of the road, although it is uncertain whether the British drove the Americans from the field, or the Americans drove off the British and were simply forced to withdraw by a lack of supplies.
The cost for Lundy's Lane affected the British commanders rather personally, as Drummond suffered a serious wound from a shot to the neck during the battle and Riall was captured by American forces. Nontheless, Drummond would insist that Lundy's Lane was a total victory for the British, and tried to smash Scott's army into the ground by chasing them to Fort Erie. However, after a winter of tremendous success on the Niagara frontier with only 5000 men spread between York and Fort Niagara, Lundy's Lane and the siege of Fort Erie, Drummond was beginning to first taste defeat. The siege would be a total failure, partially thanks to the unfortunate explosion of the fort's magazine that would wipe out an entire arm of the British attack force. Drummond's plan would be criticized as too complicated and too risky...and the cost would be extremely high for the British. The casualties number over 900...greater than one-third of the army. Drummond's own nephew, Colonel William Drummond, would be killed, but all Drummond would do is tell Prevost that the defeat was entirely due to the disgraceful conduct of his men in the attack, failing to consider his own poor plans for even a second.
Drummond would be able to regain some face when the Americans, suffering severe food shortages, withdrew from Fort Erie and allowed what remained of Drummond's army to secure the frontier. However, the summer of 1814 would be Drummond's last major military campaign. The arrival of the Duke of Wellington's veterans after the first defeat of French Emperor Napoleon Bonaparte allowed the British to launch an ultimately unsuccessful offensive into the United States, but it was Prevost, de Rottenburg, and some of Wellington's officers that would lead that attack. Drummond would remain as Lieutenant-Governor, and when Prevost was recalled to Britain for a court-martial, he took over as Governor-General and Administrator of Canada. Aside from helping establish the peace laid down by the Treaty of Ghent, his post-War of 1812 career as a civil administrator was unremarkable. In 1816, Drummond returned to Britain, where he was honoured for his contribution to the war with a knighthood and a promotion to full general. Though he remained in the military, Drummond's later life was never able to match the action of his active youth. He never again saw battle, and died on October 10, 1854, in England, one of the forgotten leaders in a war that had seen Brock and Laura Secord idolized by the Canadians, while the Drummonds, Procters, and Sheaffes of the war were relegated to obscurity.