He is best known for his field command of the mixed British-Canadian-First Nations column that captured a United States strongpoint, Fort Mackinac, on 17 July 1812 in one of the opening movements of the war.
The West Indies, then subject to frequent attacks of malaria and yellow fever, were not seen as a suitable post for a career officer with health concerns.
His new unit, the 10th Royal Veteran Battalion, arrived in Canada in 1807 for service in what was then a comparatively peaceful wing of the British Empire, far away from the Napoleonic Wars.
In November 1811 Captain Roberts even had to beg the post's resident fur trader, John Askin Jr., for point blankets in order to sew winter clothing for his garrison.
The aging and debilitated junior officer responded with surprising swiftness, organizing his blanket-cloaked men into a rapid-response force aimed at a rival United States strongpoint at Mackinac Island.
As Fort Mackinac's new commander, Captain Roberts worked to reorganize his scratch force of fur-trading militiamen into a disciplined auxiliary unit, the Michigan Fencibles.
The captain was not decorated or honored in any way for his daring 1812 command operation, and Quebec headquarters (which was actively engaged in continued combat with the American army until early 1815) ignored the shelved officer.