His family had a long history in New France, but suffered serious financial reverses due to the Seven Years' War and the siege of Quebec.

A pseudonymous letter appeared shortly afterwards in the Montreal Gazette by a "témoin oculaire" ("eye-witness") stating that the victory had been won by de Salaberry's leadership.

After the war, he took further instruction under a well-known physician in Lower Canada, Pierre de Sales Laterrière, and then continued his studies at the University of Pennsylvania in Philadelphia.

For the next twenty years, he developed a thriving practice on the south shore of the St. Lawrence, acquiring a significant social standing which later helped his political career.

[1][3] When Taché was first admitted to the practice of medicine, British doctors in Lower Canada had a monopoly over admission to the medical profession.

Taché was elected to the Quebec City board of examiners, which for the first time had a large number of Canadien doctors.

There was also a deposition by one informant in 1838, in the aftermath of the Rebellion, that Taché was active in the Frères chasseurs in the Kamouraska area, and might be planning to try to seize the lower River Saint-Lawrence.

[3] Taché actively participated in the debate on the potential creation of a Canadian confederation, defended proposals for the new form of government in part because it would serve to reaffirm Canada's link to the British Empire.

An avid supporter of the British Crown, Taché expressed ideas of loyalty even before the debates regarding the creation of Canada's confederation: "in 1848, he delivered his famous idea of French-Canadian loyalty to the British crown: ... 'we will never forget our allegiance till the last cannon which is shot on this continent in defence of Great Britain is fired by the hand of a French-Canadian'".

[14] This can certainly explain why Taché worked with future Prime Minister John A. Macdonald and other significant characters who were Fathers of the Confederation and who shared similar views.

[3] Sir Étienne-Paschal Taché's loyalty was officially recognized as an "aide-de-camp to [ Queen Victoria ], [and] held the honorary rank of a Colonel in the army".

[2][3] Taché died at age 69 in Montmagny, and is buried there at St. Odilon Cemetery, where a marker from the national Historic Sites and Monuments Board marks his grave.