He was born on 9 September 1844 in Saint-Brieuc, Côtes-d'Armor, but his father was a scion of a strongly republican Huguenot (Protestant) Nîmes family, and descended from Saint-Jean-du-Gard Camisards.

When Rossel became Minister of War, replacing Gustave Paul Cluseret after the abandonment of Fort Issy, he immediately ordered the construction of a new ring of barricades within the existing ramparts in case the Government forces penetrated the first line of defense.

Many were out of commission with their breechblocks stored in arsenals elsewhere in Paris, so that the only readily available guns were light pieces that fared poorly against the Government's heavy artillery.

On 9 May 1871 Rossel resigned from his position after a tenure of nine days, despairing of the barren prolonged deliberations of the Commune, which precluded any serious action.

We may have been beaten, but nevertheless our cannon shots have told; and I hope that the cause of democracy may find, at some future period, less unworthy and less incapable servants than ourselves.