Final answer:
The first leader of a responsible government in the Canadas in 1849 was Louis-Hippolyte LaFontaine, who played a crucial role well before Sir John A. Macdonald became the first Prime Minister of Canada in 1867.
Step-by-step explanation:
The first leader of a responsible government in the Canadas in 1849 was Louis-Hippolyte LaFontaine. Unlike the Thirteen Colonies, Canada transitioned toward independence without a revolution.
Interestingly, despite the growing pains, figures like Sir John A. Macdonald played significant roles in shaping the nation, particularly by becoming Canada's first Prime Minister in 1867.
However, when we look specifically at the emergence of responsible government, which marked a shift in how colonies were governed, allowing them more autonomy, it was LaFontaine who stepped in to lead.