He lost his re-election for the Legislative Assembly in 1836; this convinced him that reforms to the Upper Canadian political system could only happen if citizens initiated an armed conflict.

[18] His congregation agreed to baptize James after Mackenzie endured public criticism for fathering an illegitimate child and paid a fine of thirteen shillings and fourpence (equivalent to £59 in 2023) to the church.

Mackenzie sealed a capsule within the memorial's stonework containing an issue of the Colonial Advocate, the Upper Canada Gazette, some coins, and an inscription he had written.

[29] Lieutenant governor Peregrine Maitland ordered the capsule's removal a few days after it was placed in the monument because of the Colonial Advocate's critical stance of the government.

[31] Although the Colonial Advocate had the highest circulation among York newspapers, he still lost money on every issue because of low paid subscription numbers and late payments from readers.

[48] He published weekly articles in his newspaper called "The Parliament Black Book for Upper Canada, or Official Corruption and Hypocrisy Unmasked" where he listed accusations of wrongdoing by his opponents.

[51] In the election for the 11th Parliament of Upper Canada in 1830, Mackenzie campaigned for legislative control of the budget, independent judges, an executive council that would report to the legislature, and equal rights for Christian denominations.

He wanted to develop closer ties between the Reform leaders of each province and learn new techniques to oppose Upper Canada government policies.

[65] In November 1832, Goderich sent instructions to the Upper Canada lieutenant governor John Colborne to lessen the legislature's negative attitude against Mackenzie and reform the province's political and financial systems.

[64] Tories in Upper Canada were upset that Mackenzie received a positive reception from Goderich and expelled him from the legislature; he was re-elected on November 26 by his constituents.

[75] Mackenzie chose the newly built market buildings as Toronto's city hall and moved the offices of The Advocate into a southern wing of the complex.

The report expressed Mackenzie's concern on the excessive power of the executive branch in Upper Canada and the campaigning of government officials for Tory politicians during elections.

[92] Bond Head called an election in July 1836 and asked citizens to show loyalty to the British monarch by voting for Tory politicians.

[93] Bond Head's campaigning was successful and Reformers across the province lost their elections, Edward William Thomson defeating Mackenzie to represent the 2nd Riding of York in the 13th Parliament.

He cited that Upper Canadian troops were sent to suppress the Lower Canada Rebellion and a quick attack on Toronto would allow rebels to seize control of the government before a militia could be organized against them.

[112] Mackenzie grew increasingly erratic and spent the evening punishing Tory families by burning down their houses and trying to force the Upper Canada Postmaster's wife to cook meals for his rebellion.

[128] When Van Rensselaer attempted an invasion of Kingston from Hickory Island, Mackenzie refused to participate, citing a lack of confidence in the mission's success.

Mackenzie contended that Britain and the United States were at war because the British destroyed an American ship in the Caroline affair and the Neutrality Act did not apply.

After submitting his resignation from the custom house in June 1845, Mackenzie published some of the letters as Lives and Opinions of Benjamin Franklin Butler and Jesse Hoyt.

[158] In April 1846, Mackenzie published another book based on Hoyt's letters called Life and Times of Martin Van Buren: The Correspondence of His Friends, Family, and Pupils.

Mackenzie won the by-election with 294 votes, defeating Brown and H. N. Case, who both claimed to be running as Reformers, and Ronald McKinnon, the Tory Party candidate.

He was chairman of the Committee of Public Accounts while its reports criticized the province's disorganized record-keeping and exposed government expenditures that parliament had not approved.

[203] Historian Lillian F. Gates struggled to comprehend The Life and Times of Martin Van Buren because Mackenzie did not describe events chronologically and in her opinion used too many footnotes and large lists.

[206] Kilbourn stated the Colonial Advocate's articles were better when read aloud and thought Mackenzie's slow pace was similar to "a three-volume Victorian novel".

[221] According to Armstrong, Mackenzie's views on minority groups depended on their support for his policies; he was not concerned with the social standing of impoverished or oppressed people.

[218] The income gap between the richest and poorest people in Great Britain disturbed Mackenzie and he wanted to avoid this disparity in North America.

[241] He criticized a government grant given to British Wesleyans to proselytize to indigenous communities in Upper Canada, causing Egerton Ryerson and Methodists to withdraw their support for the Reform movement in 1833.

[253] In the 1830s, he advocated letting the province choose which countries it could trade with because it gave farmers access to cheaper goods and reduced Upper Canada's dependence on British markets.

[262] Many of Mackenzie's biographers agree that he delayed the implementation of responsible government because the Upper Canada Rebellion caused an exodus of Reform politicians from the colony.

[270] In the Spanish Civil War Canadian volunteers formed the Mackenzie–Papineau Battalion, naming it after Mackenzie and the leader of the Lower Canada Rebellion, Louis-Joseph Papineau.