Born in Canada, Johnston was accused of spying in 1812 and he joined the American side of the war and lived the rest of his life in the United States.
He was one of a dozen children born to British Loyalist parents [1] who fled the American Revolution in 1781 to settle in Upper Canada (now Ontario).
He married an American, Ann Randolph, in 1807 or early 1808 and began raising a family on his farm west of Kingston, Ontario.
After five years of smuggling, Bill amassed enough profit to buy a Kingston store valued at an estimated $12,000, a small fortune in that era.
Propelled by six oarsmen, this small craft gave him a distinct advantage in the shallow and tight waterways around the Thousand Islands.
Through the warm months of 1813 and 1814, he spied on the British, attacked their supply boats, robbed mail couriers, burned ships, and participated in the battles of Sackets Harbor and Crysler's Farm.
In early December, 1837, a small band of men, led by former Toronto mayor, William Lyon Mackenzie rebelled against British rule.
His small force was quickly defeated at Montgomery's Tavern, and Mackenzie fled to Navy Island, near the Canada–US border.
On 29 December, an Anglo-Canadian force crossed the icy river and destroyed Mackenzie's supply ship, the Caroline, during which an American sailor was killed.
Johnston helped plan an attack on Upper Canada near Detroit led by Donald McLeod in February 1838.
Following a plan Johnston hatched with Donald McLeod (a general in the Patriot army), they and twenty others, mostly Canadians, set out to capture the passenger steamer, the Sir Robert Peel.
[citation needed] (In mid-July 1838, the US asked the British to stay out, so angry were its citizens to see foreign warships in their waters.
In November 1838, a force of 250 American Hunter Patriots crossed the St. Lawrence River at Ogdensburg, New York for an abortive attack on Prescott.
On the first day of the battle, Johnston ferried supplies to the Canadian shore and helped to refloat two rebel schooners that ran aground on the mud flats.