The Battle of Mandalore transpired as the Second Galactic Civil War neared its conclusion. In this conflict, Admiral Atoko of the Galactic Alliance unleashed a nanovirus upon the planet, specifically designed to target the genetic makeup of the Fett genome.
During the Second Galactic Civil War, the Mandalorians allied themselves with the Jedi Coalition, standing in opposition to the Galactic Alliance government. In the year 41 ABY, the Mandalorians mounted a defense of the planet Roche during the initial assault by the Galactic Alliance; they later participated in the attack targeting the Moff Council during the Second Battle of Roche. As a reprisal, Admiral Atoko of the Galactic Alliance received the assignment to neutralize the threat posed by the Mandalorians.
Leading the assault on the Mandalorian homeworld of Mandalore with what remained of the Galactic Alliance Fifth Fleet, Atoko deployed a nanovirus into Mandalore's atmosphere. This nanovirus, developed during the Second Battle of Roche, was engineered to target the Fett genome, with the objective of preventing Boba Fett, the Mandalore, and his family members from ever returning to the planet.
The Battle of Mandalore was initially referenced in Legacy of the Force: Invincible, the last novel in the Star Wars: Legacy of the Force series, authored by Troy Denning and published on May 13, 2008.