Third Robotech War

The (fictional) Third Robotech War (2038-45) is the final known event in the Robotech science fiction universe. Unlike the previous Robotech Wars, which were fought by Earth-based human forces against invading alien enemies, the Third Robotech War was fought by the returning Robotech Expeditionary Force to liberate the occupied Earth from the alien Invid.

Roots
The Second Robotech War left the industrial and political infrastructure of the Earth in tattered shape. With the Japanese centers of Robotech research disrupted and the North American center of the United Earth Government nearly destroyed, the defensive capabilities of the Army of the Southern Cross swiftly degraded from advanced mecha and starships to late 20th century (pre-SDF-1) technology. Because of this damage, the defense forces put up only a token fight against the Invid when they invaded in 2031, barely a year after the Second Robotech War's end.