John Macdonell was a Lieutenant Colonel and aide-de-camp to British general Isaac Brock, who famously fell in the Battle of Queenston Heights. The Americans had captured the high ground and the British battery, which had driven Brock to personally attack as he felt the fate of the entire colony was at stake. Upon Brock's death, command fell to Macdonell who, despite limited experience, led the York Militia and along with the 49th Foot nearly recaptured it before Macdonell too was shot, dying of his wounds.

The battle raged on, but while the British received more reinforcements from Fort George, American militia on the other side of the Niagara River refused to cross, upon hearing the war cries of Mohawks allied to the British. This eventually turned the tide of the battle in favour of the British.

While Brock was remembered as the saviour of Canada, he never really wanted to be in Canada. He was a career soldier and, like many of the era, sought action and glory on the battlefields of Europe against Napoleon -- and not in a backwater provincial posting. To his credit, he decided to remain and do his duty to defend Upper Canada when war was imminent. Brock was held in great esteem by his troops, the colonists and his native allies (Tecumseh included) even before Queenston Heights, and his knighthood for capturing Detroit was on its way when he died.

Macdonell in contrast was more like a "native son" of the colony. Although he was born in Scotland, he had lived in Canada since he was seven years old. He wasn't a career soldier but a civilian and lawyer (and Attorney General of Upper Canada at the time). He had made the same sacrifices in battle, but he received little recognition from Britain or the colony he had died defending. Brock has a massive monument at Queenston, while Macdonell -- the actual native son of Canada, "one of us", etc. -- is barely acknowledged.

This was probably the gist of Rogers' lament for Macdonell.