In Ender’s world, there had been a devastating battle with the Buggers; this is a time of rebuilding as the military trained new leaders. As the story opens, the government had been monitoring many young persons, notably Ender’s brother Peter and sister Valentine. These two monitorings proved that neither was acceptable (Card leaves the reasons open to the reader’s conjecture, but the implication is that Peter was too violent and Valentine was not aggressive enough). Ender (the socially frowned-upon Third child) only gets a chance because the military monitors found a lot of potential in the Wiggin genes. As the book cover puts it, “Earth is under attack. An alien species (the Buggers) is poised for a final assault." As in all science fiction, there is danger in placing the book in our own historical time (it was written in 1977) or trying to find a parallel in history, although there are plenty of suggestions in the text that Card had the American/Russian Cold War in mind, at least partially.