After his graduation from college, Febvre taught at a provincial lycée, where he worked on his thesis on Philip II of Spain and the Franche-Comté.

After the outbreak of World War I in 1914, Febvre was forced to leave his teaching post to join the army, where he served for four years.

Febvre reconstructed the life of villagers and town dwellers in a small traditional province in France by contextualizing historical events in terms of the geography and environment of the times.

By describing Franche-Comté's rivers, salt mines, vineyards and other surroundings, Febvre created an accurate and true-to-life portrayal of the atmosphere and outlook of the time.

Published in the Revue Historique in 1929, "Une question mal posée" attempted to study popular religion by trying to observe and quantify human behavior.

Through an enormous amount of research, Febvre collected information from various monasteries and chapels to study the influence of new wave philosophy in religion and the clergy's approach to understanding and translating their views to lay people.

He became convinced that changing religious views and attitudes is as difficult as trying to influence the outcome of any sort of political or social upheavals.

He published vigorously throughout the 1930s and early 40s, although World War II interrupted his work (following the Fall of France, parts of the country were occupied by Germany).

Bloch, forced to accede, turned the Annales over to the sole editorship of Febvre, who then changed the journal's name to Mélanges d'Histoire Sociale.

In June 1944, Marc Bloch was executed, and so Febvre became the man who carried the Annales into the post-war period, most notably by training Fernand Braudel and co-founding the VI section of the École Pratique des Hautes Etudes, later known as École des Hautes Études en Sciences Sociales (EHESS).