Lower Canada Rebellion
When news of the arrest of the Patriote leaders reached Upper Canada, William Lyon Mackenzie launched an armed rebellion in December 1837. In the meantime, filibusters from the United States, the Hunter Patriots, formed a small militia and attacked Windsor, Upper Canada, to support the Canadian Patriots. This resulted in the declaration of martial law by the Lower Canadian government.
Caroline affair
The Reform Movement of Upper Canada (today's Ontario) was a movement to make the British colonial rule in Canada more democratic and less corrupt. William Lyon Mackenzie was one of the key leaders of this movement. He was repeatedly elected to serve in a hostile parliament that repeatedly ejected him for his reform efforts. By 1837, Mackenzie had given up on peaceful means for reform and began to prepare for an uprising.