[citation needed] Alexis joined the army in the 1830s, serving President Jean-Louis Pierrot, his father-in-law, as an aide-de-camp.

Troops loyal to Firmin were finally defeated in Port-au-Prince, leaving only two strongholds, Saint-Marc and Gonaïves, opposed to the new government of Canal and Alexis.

Alexis took advantage of the situation by negotiating with the United States and declaring himself in support of American interests in the Caribbean.

The U.S. responded by imposing a naval blockade on the two centers still loyal to Firmin, paving the way for Alexis to seize control of the government for himself.

In 1903, he proclaimed Eugène Francois Magloire Commandant of Grande-Rivière du Nord, General of division of the republic and his honorary aide-de-camp.