Colonization is a trilogy of books that serve as a sequel to the Worldwar series, part of the Worldwar franchise. The trilogy chronicles the arrival of the Race's Colonization Fleet on Earth in the 1960s. The trilogy is followed by the novel Homeward Bound.
The Race has settled and plans to colonize nearly half the surface of the Earth. This half includes Africa, Australia, China, southern Asia, Central America, South America, Spain, and Poland (consisting of the territory of prewar Poland and East Prussia). The United States, Canada, the Soviet Union, the Greater German Reich (Germany and the territories it occupied during World War II), Great Britain, and Japan are the only other powers when the Race's colonization fleet of eighty to one hundred million settlers arrives. Humanity and the Race still jockey for advantages over each other.
The Race spend their time trying to adapt to conditions on Earth (e.g., the aliens release species from Home on Earth, causing environmental trouble). The USSR supplies weapons to Mao Tse-Tung's Chinese Communist Party, the Greater German Reich attacks Race-held Poland (and fails, resulting in the death of Führer Ernst Kaltenbrunner, his top officials, the nuclear destruction of much of Greater Germany (including the capital city Nuremberg, and the removal of Nazi space installations). The German capital is relocated to Flensburg and Walter Dornberger becomes the new Führer. The United States is led by President Earl Warren. The Soviet Union is ruled by Ex-Foreign Commissar Vyacheslav Molotov.
The Race's initial invasion has benefited the technology of humanity. With the end to the second round of fighting, alien technology is being rapidly absorbed by humanity. Although the Race remains superior in technology, they are swiftly losing ground as human technology advances. Evidence of this being that all human superpowers have spacecraft floating among the asteroid belt. The Americans have also launched two human starships. The Soviet Union, United States, and Germany established a Moon base and the U.S. and Germany put a man on Mars, but Germany was first.