He served one term in the Legislative Assembly of the Province of Canada, as a supporter of Louis-Joseph Papineau and Denis-Benjamin Viger.

His father, Joseph, was a farmer and then a sea captain, who engaged in a legal battle with Robert Christie, a prominent lawyer and member of the Legislative Assembly of Lower Canada.

He started by publishing letters and poetry on political matters in the newspaper Le Populaire, under the pseudonym "Marie-Louise".

After the Rebellion had been suppressed, Barthe wrote a poem Aux exilés politiques canadiens, which appeared in Le Fantasque on December 26, 1838.

In this, he took a similar position to Étienne Parent, who wrote and lectured on the need for French-Canadians to expand from the traditional economic activities of rural life and the professions.

He was elected to the Legislative Assembly of the Province of Canada for the Yamaska riding, defeating a pro-union candidate, Jonathan Würtele.

One of the leaders of the French-Canadian Group, John Neilson, introduced a motion condemning the way the union had been imposed on Lower Canada without consent.

All of the members of the French-Canadian Group, including Barthe, voted in favour of the motion and against the union, as did some of the reformers from Upper Canada.

Louis Hippolyte LaFontaine and Robert Baldwin had been admitted to the Executive Council the year before, but they now reached an impasse with the new Governor General, Sir Charles Metcalfe.

Shortly afterwards, Metcalfe appointed Viger and a conservative member from Upper Canada, William Draper, to the Council.

[11][12] The reason Viger supported Metcalfe was that he disagreed with LaFontaine's approach of an alliance with Upper Canada reformers.

Once Viger was in office, Barthe naturally took his patron's position, and in his newspaper articles in L'Aurora des Canadas was sharply critical of LaFontaine.

He attempted to appoint his brother-in-law as his deputy, but most of the judges of the Court refused to accept that arrangement and would only sit with Barthe as clerk.

[2][15] Barthe had become very active in the new Institut canadien de Montréal, an association of relatively young professionals of liberal tendencies, which provided a forum for discussions and public lectures.

The book went into Canadian political history in great detail, but from a strongly partisan view, praising the Parti rouge and attacking LaFontaine.

[1][2][3][17] In 1855, he returned to Canada, initially settling in Trois-Rivières, where he was the editor for two different newspapers, L'Ère nouvelle and Le Bas-Canada, the latter founded by his brother.

Late in 1856, he moved to Quebec City where, at the request of Étienne Parent, he was co-editor of Le Canadien until 1862, his last major editorial role.

He had a tendency to exaggerate the roles he played, and to outright invent events that historical research shows did not occur.

[1][2] His daughter Émilie Barthe eventually gained some notoriety, as the close friend of Prime Minister Wilfrid Laurier.