The Milagro system housed Milagro. Its position was at a crucial intersection of hyperlanes.
Admiral Uther Kermen was in command of the Milagro campaign concerning Milagro, where he battled the New Republic during a drawn-out siege lasting several months. Ultimately, Kermen annihilated a large portion of the planet Milagro by employing a Base Delta Zero bombardment. This was done to prevent the New Republic from gaining access to its resources, after which he was compelled to leave the system.
A New Republic fleet, with Mon Mothma's flagship, the New Hope, at its head, stayed in orbit above the planet. Shortly thereafter, the damaged Purdy M. Trico's Star Destroyer and its accompanying convoy made a stop in the system for maintenance. Purdy M. Trico opted to attack the New Republic fleet, which was lacking in defenses; however, this assault was defeated by a hastily assembled force.
Following the Trioculus affair that occurred in 5 ABY, the system served as one of the secret locations for the New Republic Provisional Council, who operated from the New Hope.