On 1 January 1870, he entered the École d'état-major (Staff College), but the Franco-Prussian War made him leave school in October 1870 to join the 13th Army Corps and he served at the Siege of Paris as a lieutenant.

Michel was appointed to the Superior War Council on 22 December 1907, which was largely concerned with strategic planning.

[1] Michel was highly successful in training reservists, a goal that especially appealed to the Republican political element in France.

Michel was appointed Vice President High Council of War on 10 January 1911, which made him Commander in Chief designate of the French Army.

However, the more conservative elements who largely dominated the senior ranks of the French Army were deeply suspicious of the Republicanism of the reservists, and believed they would be inferior soldiers.

Under the current Plan XVI French planners predicted the main German offensive to come in Lorraine with a secondary attack through south-eastern Belgium and Luxembourg towards Mézières.

They complained that Michel's approach was strategically too defensive and ran against the French Army's offensive spirit.

The new Plan XVII drafted by Joseph Joffre was now adopted, rejected Michel's ideas and emphasised a massive French attack in Lorraine.

On 26 August 1914, War Minister Messimy dismissed him as military governor of Paris and replaced him with General Joseph Gallieni.